For the latest data from the 2023-24 Religious Landscape Study (RLS) on Americans’ religious identities, beliefs and practices, read our report “Decline of Christianity in the U.S. Has Slowed, May Have Leveled Off” and visit the interactive database “Religious Landscape Study.”

The Christian share of the U.S. population is declining, while the number of U.S. adults who do not identify with any organized religion is growing, according to an extensive new survey by the Pew Research Center. Moreover, these changes are taking place across the religious landscape, affecting all regions of the country and many demographic groups. While the drop in Christian affiliation is particularly pronounced among young adults, it is occurring among Americans of all ages. The same trends are seen among whites, blacks and Latinos; among both college graduates and adults with only a high school education; and among women as well as men. (Explore the data with our interactive database tool.)

To be sure, the United States remains home to more Christians than any other country in the world, and a large majority of Americans – roughly seven-in-ten – continue to identify with some branch of the Christian faith.¹ But the major new survey of more than 35,000 Americans by the Pew Research Center finds that the percentage of adults (ages 18 and older) who describe themselves as Christians has dropped by nearly eight percentage points in just seven years, from 78.4% in an equally massive Pew Research survey in 2007 to 70.6% in 2014. Over the same period, the percentage of Americans who are religiously unaffiliated – describing themselves as atheist, agnostic or “nothing in particular” – has jumped more than six points, from 16.1% to 22.8%. And the share of Americans who identify with non-Christian faiths also has inched up, rising 1.2 percentage points, from 4.7% in 2007 to 5.9% in 2014. Growth has been especially great among Muslims and Hindus, albeit from a very low base.

The drop in the Christian share of the population has been driven mainly by declines among mainline Protestants and Catholics. Each of those large religious traditions has shrunk by approximately three percentage points since 2007. The evangelical Protestant share of the U.S. population also has dipped, but at a slower rate, falling by about one percentage point since 2007.²

Even as their numbers decline, American Christians – like the U.S. population as a whole – are becoming more racially and ethnically diverse. Non-Hispanic whites now account for smaller shares of evangelical Protestants, mainline Protestants and Catholics than they did seven years earlier, while Hispanics have grown as a share of all three religious groups. Racial and ethnic minorities now make up 41% of Catholics (up from 35% in 2007), 24% of evangelical Protestants (up from 19%) and 14% of mainline Protestants (up from 9%).

Religious intermarriage also appears to be on the rise: Among Americans who have gotten married since 2010, nearly four-in-ten (39%) report that they are in religiously mixed marriages, compared with 19% among those who got married before 1960.³ The rise in intermarriage appears to be linked with the growth of the religiously unaffiliated population. Nearly one-in-five people surveyed who got married since 2010 are either religiously unaffiliated respondents who married a Christian spouse or Christians who married an unaffiliated spouse. By contrast, just 5% of people who got married before 1960 fit this profile.

Explore data on religious groups in the U.S. by affiliation, geographic and demographic information.

While many U.S. religious groups are aging, the unaffiliated are comparatively young – and getting younger, on average, over time. As a rising cohort of highly unaffiliated Millennials reaches adulthood, the median age of unaffiliated adults has dropped to 36, down from 38 in 2007 and far lower than the general (adult) population’s median age of 46.⁴ By contrast, the median age of mainline Protestant adults in the new survey is 52 (up from 50 in 2007), and the median age of Catholic adults is 49 (up from 45 seven years earlier).

These are among the key findings of the Pew Research Center’s second U.S. Religious Landscape Study, a follow-up to its first comprehensive study of religion in America, conducted in 2007.

Because the U.S. census does not ask Americans about their religion, there are no official government statistics on the religious composition of the U.S. public.⁵ Some Christian denominations and other religious bodies keep their own rolls, but they use widely differing criteria for membership and sometimes do not remove members who have fallen away.⁶ Surveys of the general public frequently include a few questions about religious affiliation, but they typically do not interview enough people, or ask sufficiently detailed questions, to be able to describe the country’s full religious landscape.

The Religious Landscape Studies were designed to fill the gap. Comparing two virtually identical surveys, conducted seven years apart, can bring important trends into sharp relief. In addition, the very large samples in both 2007 and 2014 included hundreds of interviews with people from small religious groups that account for just 1% or 2% of the U.S. population, such as Mormons, Episcopalians and Seventh-day Adventists. This makes it possible to paint demographic and religious profiles of numerous denominations that cannot be described by smaller surveys. The most recent Religious Landscape Study also was designed to obtain a minimum of 300 interviews with respondents in each state and the District of Columbia as well as to represent the country’s largest metropolitan areas, enabling an assessment of the religious composition not just of the nation as a whole, but also of individual states and localities. (See Appendix D.)

The latest survey was conducted in English and Spanish among a nationally representative sample of 35,071 adults interviewed by telephone, on both cellphones and landlines, from June 4-Sept. 30, 2014. Findings based on the full sample have a margin of sampling error of plus or minus 0.6 percentage points. The survey is estimated to cover 97% of the non-institutionalized U.S. adult population; 3% of U.S. adults are not reachable by telephone or do not speak English or Spanish well enough to participate in the survey. (See Appendix A for more information on how the survey was conducted, margins of error for subgroups analyzed in this report and additional details.)

Even a very small margin of error, when applied to the hundreds of millions of people living in the United States, can yield a wide range of estimates for the size of particular faiths. Nevertheless, the results of the second Religious Landscape Study indicate that Christians probably have lost ground, not only in their relative share of the U.S. population, but also in absolute numbers.

In 2007, there were 227 million adults in the United States, and a little more than 78% of them – or roughly 178 million – identified as Christians. Between 2007 and 2014, the overall size of the U.S. adult population grew by about 18 million people, to nearly 245 million.⁷ But the share of adults who identify as Christians fell to just under 71%, or approximately 173 million Americans, a net decline of about 5 million.

This decline is larger than the combined margins of sampling error in the twin surveys conducted seven years apart. Using the margins of error to calculate a probable range of estimates, it appears that the number of Christian adults in the U.S. has shrunk by somewhere between 2.8 million and 7.8 million.⁸

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Of the major subgroups within American Christianity, mainline Protestantism – a tradition that includes the United Methodist Church, the American Baptist Churches USA, the Evangelical Lutheran Church in America, the Presbyterian Church (U.S.A.) and the Episcopal Church, among others – appears to have experienced the greatest drop in absolute numbers. In 2007, there were an estimated 41 million mainline Protestant adults in the United States. As of 2014, there are roughly 36 million, a decline of 5 million – although, taking into account the surveys’ combined margins of error, the number of mainline Protestants may have fallen by as few as 3 million or as many as 7.3 million between 2007 and 2014.⁹

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By contrast, the size of the historically black Protestant tradition – which includes the National Baptist Convention, the Church of God in Christ, the African Methodist Episcopal Church, the Progressive Baptist Convention and others – has remained relatively stable in recent years, at nearly 16 million adults. And evangelical Protestants, while declining slightly as a percentage of the U.S. public, probably have grown in absolute numbers as the overall U.S. population has continued to expand.

 

 

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The new survey indicates that churches in the evangelical Protestant tradition – including the Southern Baptist Convention, the Assemblies of God, Churches of Christ, the Lutheran Church-Missouri Synod, the Presbyterian Church in America, other evangelical denominations and many nondenominational congregations – now have a total of about 62 million adult adherents. That is an increase of roughly 2 million since 2007, though once the margins of error are taken into account, it is possible that the number of evangelicals may have risen by as many as 5 million or remained essentially unchanged.¹⁰

 

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Like mainline Protestants, Catholics appear to be declining both as a percentage of the population and in absolute numbers. The new survey indicates there are about 51 million Catholic adults in the U.S. today, roughly 3 million fewer than in 2007. But taking margins of error into account, the decline in the number of Catholic adults could be as modest as 1 million.¹¹ And, unlike Protestants, who have been decreasing as a share of the U.S. public for several decades, the Catholic share of the population has been relatively stable over the long term, according to a variety of other surveys (see Appendix C).

 

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Meanwhile, the number of religiously unaffiliated adults has increased by roughly 19 million since 2007. There are now approximately 56 million religiously unaffiliated adults in the U.S., and this group – sometimes called religious “nones” – is more numerous than either Catholics or mainline Protestants, according to the new survey. Indeed, the unaffiliated are now second in size only to evangelical Protestants among major religious groups in the U.S.

 

 

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Factors Behind the Changes in Americans’ Religious Identification

One of the most important factors in the declining share of Christians and the growth of the “nones” is generational replacement. As the Millennial generation enters adulthood, its members display much lower levels of religious affiliation, including less connection with Christian churches, than older generations. Fully 36% of young Millennials (those between the ages of 18 and 24) are religiously unaffiliated, as are 34% of older Millennials (ages 25-33). And fewer than six-in-ten Millennials identify with any branch of Christianity, compared with seven-in-ten or more among older generations, including Baby Boomers and Gen-Xers. Just 16% of Millennials are Catholic, and only 11% identify with mainline Protestantism. Roughly one-in-five are evangelical Protestants.

However, generational replacement is by no means the only reason that religious “nones” are growing and Christians are declining. In addition, people in older generations are increasingly disavowing association with organized religion. About a third of older Millennials (adults currently in their late 20s and early 30s) now say they have no religion, up nine percentage points among this cohort since 2007, when the same group was between ages 18 and 26. Nearly a quarter of Generation Xers now say they have no particular religion or describe themselves as atheists or agnostics, up four points in seven years. Baby Boomers also have become slightly but noticeably more likely to identify as religious “nones” in recent years.

As the shifting religious profiles of these generational cohorts suggest, switching religion is a common occurrence in the United States. If all Protestants were treated as a single religious group, then fully 34% of American adults currently have a religious identity different from the one in which they were raised. This is up six points since 2007, when 28% of adults identified with a religion different from their childhood faith. If switching among the three Protestant traditions (e.g., from mainline Protestantism to the evangelical tradition, or from evangelicalism to a historically black Protestant denomination) is added to the total, then the share of Americans who currently have a different religion than they did in childhood rises to 42%.

By a wide margin, religious “nones” have experienced larger gains through religious switching than any other group. Nearly one-in-five U.S. adults (18%) were raised in a religious faith and now identify with no religion. Some switching also has occurred in the other direction: 9% of American adults say they were raised with no religious affiliation, and almost half of them (4.3% of all U.S. adults) now identify with some religion. But for every person who has joined a religion after having been raised unaffiliated, there are more than four people who have become religious “nones” after having been raised in some religion. This 1:4 ratio is an important factor in the growth of the unaffiliated population.

By contrast, Christianity – and especially Catholicism – has been losing more adherents through religious switching than it has been gaining. More than 85% of American adults were raised Christian, but nearly a quarter of those who were raised Christian no longer identify with Christianity. Former Christians represent 19.2% of U.S. adults overall.

Both the mainline and historically black Protestant traditions have lost more members than they have gained through religious switching, but within Christianity the greatest net losses, by far, have been experienced by Catholics. Nearly one-third of American adults (31.7%) say they were raised Catholic. Among that group, fully 41% no longer identify with Catholicism. This means that 12.9% of American adults are former Catholics, while just 2% of U.S. adults have converted to Catholicism from another religious tradition. No other religious group in the survey has such a lopsided ratio of losses to gains.

The evangelical Protestant tradition is the only major Christian group in the survey that has gained more members than it has lost through religious switching. Roughly 10% of U.S. adults now identify with evangelical Protestantism after having been raised in another tradition, which more than offsets the roughly 8% of adults who were raised as evangelicals but have left for another religious tradition or who no longer identify with any organized faith.

Other highlights in this report include:

• The Christian share of the population is declining and the religiously unaffiliated share is growing in all four major geographic regions of the country. Religious “nones” now constitute 19% of the adult population in the South (up from 13% in 2007), 22% of the population in the Midwest (up from 16%), 25% of the population in the Northeast (up from 16%) and 28% of the population in the West (up from 21%). In the West, the religiously unaffiliated are more numerous than Catholics (23%), evangelicals (22%) and every other religious group.
• Whites continue to be more likely than both blacks and Hispanics to identify as religiously unaffiliated; 24% of whites say they have no religion, compared with 20% of Hispanics and 18% of blacks. But the religiously unaffiliated have grown (and Christians have declined) as a share of the population within all three of these racial and ethnic groups.
• The percentage of college graduates who identify with Christianity has declined by nine percentage points since 2007 (from 73% to 64%). The Christian share of the population has declined by a similar amount among those with less than a college education (from 81% to 73%). Religious “nones” now constitute 24% of all college graduates (up from 17%) and 22% of those with less than a college degree (up from 16%).
• More than a quarter of men (27%) now describe themselves as religiously unaffiliated, up from 20% in 2007. Fewer women are religious “nones,” but the religiously unaffiliated are growing among women at about the same rate as among men. Nearly one-in-five women (19%) now describe themselves as religiously unaffiliated, up from 13% in 2007.
• Although it is low relative to other religious groups, the retention rate of the unaffiliated has increased. In the current survey, 53% of those raised as religiously unaffiliated still identify as “nones” in adulthood, up seven points since 2007. And among Millennials, “nones” actually have one of the highest retention rates of all the religious categories that are large enough to analyze in the survey.
• As the ranks of the religiously unaffiliated continue to grow, they also describe themselves in increasingly secular terms. In 2007, 25% of the “nones” called themselves atheists or agnostics; 39% identified their religion as “nothing in particular” and also said that religion is “not too” or “not at all” important in their lives; and 36% identified their religion as “nothing in particular” while nevertheless saying that religion is either “very important” or “somewhat important” in their lives. The new survey finds that the atheist and agnostic share of the “nones” has grown to 31%. Those identifying as “nothing in particular” and describing religion as unimportant in their lives continue to account for 39% of all “nones.” But the share identifying as “nothing in particular” while also affirming that religion is either “very” or “somewhat” important to them has fallen to 30% of all “nones.”
• While the mainline Protestant share of the population is significantly smaller today than it was in 2007, the evangelical Protestant share of the population has remained comparatively stable (ticking downward slightly from 26.3% to 25.4% of the population). As a result, evangelicals now constitute a clear majority (55%) of all U.S. Protestants. In 2007, roughly half of Protestants (51%) identified with evangelical churches.
• Since 2007, the share of evangelical Protestants who identify with Baptist denominations has shrunk from 41% to 36%. Meanwhile, the share of evangelicals identifying with nondenominational churches has grown from 13% to 19%.
• The United Methodist Church (UMC) continues to be the largest denomination within the mainline Protestant tradition. Currently, 25% of mainline Protestants identify with the UMC, down slightly from 28% in 2007.
• More than six-in-ten people in the historically black Protestant tradition identify with Baptist denominations, including 22% who identify with the National Baptist Convention, the largest denomination within the historically black Protestant tradition.
• The share of the public identifying with religions other than Christianity has grown from 4.7% in 2007 to 5.9% in 2014. Gains were most pronounced among Muslims (who accounted for 0.4% of respondents in the 2007 Religious Landscape Study and 0.9% in 2014) and Hindus (0.4% in 2007 vs. 0.7% in 2014).¹²
• Roughly one-in-seven participants in the new survey (15%) were born outside the U.S., and two-thirds of those immigrants are Christians, including 39% who are Catholic. More than one-in-ten immigrants identify with a non-Christian faith, such as Islam or Hinduism.
• Hindus and Jews continue to be the most highly educated religious traditions. Fully 77% of Hindus are college graduates, as are 59% of Jews (compared with 27% of all U.S. adults). These groups also have above-average household incomes. Fully 44% of Jews and 36% of Hindus say their annual family income exceeds $100,000, compared with 19% of the public overall.

About the 2014 U.S. Religious Landscape Study

This is the first report on findings from the 2014 U.S. Religious Landscape Study, the centerpiece of which is a nationally representative telephone survey of 35,071 adults. This is the second time the Pew Research Center has conducted a Religious Landscape Study. The first was conducted in 2007, also with a telephone survey of more than 35,000 Americans.

The new study is designed to serve three main purposes:

• To provide a detailed account of the size of the religious groups that populate the U.S. landscape;
• To describe the demographic characteristics, religious beliefs and practices, and social and political values of those religious groups; and
• To document how the religious profile of the U.S. has changed since the first study was conducted in 2007. With more than 35,000 interviews each, both the 2007 and 2014 studies have margins of error of less than one percentage point, making it possible to identify even relatively small changes in religious groups’ share of the U.S. population.

The results of the 2014 Religious Landscape Study will be published in a series of reports over the coming year. This first report focuses on the changing religious composition of the U.S. and describes the demographic characteristics of U.S. religious groups, including their median age, racial and ethnic makeup, nativity data, education and income levels, gender ratios, family composition (including religious intermarriage rates) and geographic distribution. It also summarizes patterns in religious switching.

In addition, this report includes an appendix that compares the findings of the 2007 and 2014 Religious Landscape Studies with several other surveys and assesses how recent developments in American religion fit into longer-term trends. Data from a variety of national surveys, including the long-running General Social Survey and Gallup polls, confirm that Protestants have been declining as a share of the U.S. population and that the unaffiliated have been growing. But there is less of a consensus about trends in American Catholicism. Some surveys, including the one featured in this report, indicate that the Catholic share of the population is declining, while others suggest it is relatively stable or may have declined and then ticked back up in recent years. (See Appendix C.)

Other findings from the 2014 Religious Landscape Study will be released later this year. In addition to the written reports, the Religious Landscape Study’s findings will be available through a new interactive tool. The online presentation allows users to delve more deeply into the survey’s findings, build interactive maps or charts and explore the data most interesting to them.

Acknowledgments

Many individuals from the Pew Research Center contributed to this report. Alan Cooperman, director of religion research, oversaw the effort and served as the primary editor. Gregory Smith, associate director for religion research, served as the primary researcher and wrote the Overview and Methodology. Smith also wrote the chapter on the changing religious composition of the U.S., the appendix on the classification of Protestant denominations and the appendix on putting the findings from the Religious Landscape Study into context. The chapter on religious switching and intermarriage was written by Research Associate Becka Alper. Research Associate Jessica Martinez and Research Assistant Claire Gecewicz wrote the chapter on the demographic profiles of religious groups, and Research Analyst Elizabeth Sciupac wrote the chapter on the shifting religious identity of demographic groups. Gecewicz prepared the detailed tables. The report was number checked by Alper, Gecewicz, Martinez, Sciupac and Research Associate Besheer Mohamed. The report was edited by Sandra Stencel, Michael Lipka, Caryle Murphy and Aleksandra Sandstrom. Bill Webster created the graphics. Stacy Rosenberg, Russell Heimlich, Diana Yoo, Besheer Mohamed, Ben Wormald and Juan Carlos Esparza Ochoa developed the interactive tool.

The Pew Research Center’s methods team provided advice on the sampling plan, questionnaire design, weighting strategy and data analysis. The methods team, led by Director of Survey Research Scott Keeter, includes Research Methodologists Kyley McGeeney and Andrew Mercer, Research Assistant Nicholas Hatley and graduate student intern H. Yanna Yan.

Others at the Pew Research Center who provided research guidance include Michael Dimock, Claudia Deane, Andy Kohut and Conrad Hackett. Communications support was provided by Katherine Ritchey, Stefan Cornibert, Russ Oates and Robyn Tomlin.

John C. Green, director of the Ray C. Bliss Institute of Applied Politics at the University of Akron, served as a senior adviser on the Religious Landscape Studies, providing valuable advice on the survey questionnaires, categorization of respondents and drafts of the reports. Additionally, we received helpful comments on portions of the 2014 study from David E. Campbell, director, Rooney Center for the Study of American Democracy, University of Notre Dame; William D’Antonio, senior fellow, Institute for Policy Research and Catholic Studies, The Catholic University of America; Mike Hout, professor of sociology, New York University; and Barry Kosmin, director, Institute for the Study of Secularism in Society and Culture, Trinity College. We also received valuable advice from Luis Lugo, former director of the Pew Research Center’s Religion & Public Life project, and Paul Taylor, former executive vice president of the Pew Research Center.

Funding for the 2014 Religious Landscape Study comes from The Pew Charitable Trusts, which received generous support for the project from the Lilly Endowment Inc.

While the analysis was guided by our consultations with the advisers, the Pew Research Center is solely responsible for the interpretation and reporting of the data.

Roadmap to the Report

The remainder of this report explores in greater depth many of the key findings summarized in this Overview. Chapter 1 offers a detailed look at the religious composition of the United States and how it has changed in recent years. Chapter 2 examines patterns in religious switching and intermarriage. Chapter 3 provides a demographic profile of the major religious traditions in the United States. Chapter 4 then flips the lens, looking at the religious profile of Americans in various demographic groups. Appendix A describes the methodology used to conduct the study. Appendix B provides details on how Protestants were categorized into one of three major Protestant traditions (the evangelical tradition, the mainline tradition and the historically black Protestant tradition) based on the specific denomination with which they identify. Appendix C compares findings from the Religious Landscape Studies with other major religion surveys and puts the current results into the context of longer-term trends.

Christians remain by far the largest religious group in the United States, but the Christian share of the population has declined markedly. In the past seven years, the percentage of adults who describe themselves as Christians has dropped from 78.4% to 70.6%.

Once an overwhelmingly Protestant nation, the U.S. no longer has a Protestant majority. In 2007, when the Pew Research Center conducted its first Religious Landscape Study, more than half of adults (51.3%) identified as Protestants. Today, by comparison, 46.5% of adults describe themselves as Protestants.

While there have been declines across a variety of Protestant denominations, the most pronounced changes have occurred in churches in the mainline Protestant tradition, such as the United Methodist Church and the Evangelical Lutheran Church in America. The share of adults belonging to mainline churches dropped from 18.1% in 2007 to 14.7% in 2014. This is similar to the drop seen among U.S. Catholics, whose share of the population declined from 23.9% to 20.8% during the same seven-year period.

In contrast with mainline Protestantism, there has been less change in recent years in the proportion of the population that belongs to churches in the evangelical or historically black Protestant traditions. Evangelicals now make up a clear majority (55%) of all U.S. Protestants. In 2007, 51% of U.S. Protestants identified with evangelical churches.

While the overall Christian share of the population has dropped in recent years, the number of Americans who do not identify with any religion has soared. Nearly 23% of all U.S. adults now say they are religiously unaffiliated, up from about 16% in 2007. While most of the unaffiliated describe themselves as having “no particular religion,” a growing share say they are atheists or agnostics.

This chapter takes a close look at the current religious composition of the United States and how it has changed since 2007. A full-page table (PDF) summarizes the religious affiliation of U.S. adults in a way that captures small groups that make up less than 1% of the population.

The chapter also explains how Protestant respondents were sorted into the three distinct Protestant traditions – the evangelical Protestant tradition, the mainline Protestant tradition and the historically black Protestant tradition – and it documents which Protestant denominations are shrinking, and which are growing.

Finally, the chapter examines the growth of non-Christian religions in the U.S. and takes a closer look at the composition of the religiously unaffiliated population.

Measuring and Categorizing Protestantism

American Protestantism is diverse, encompassing more than a dozen major denominational families – such as Baptists, Methodists, Lutherans and Pentecostals – all with unique beliefs, practices and histories. These denominational families, in turn, are made up of a host of different denominations, such as the Southern Baptist Convention, the American Baptist Churches USA and the National Baptist Convention.

Because of this great diversity, American Protestantism is best understood not as a single religious tradition but rather as three distinct traditions – the evangelical Protestant tradition, the mainline Protestant tradition and the historically black Protestant tradition. Each of these traditions is made up of numerous denominations and congregations that share similar beliefs, practices and histories.

For instance, churches within the evangelical tradition tend to share religious beliefs (including the conviction that personal acceptance of Jesus Christ is the only way to salvation), practices (like an emphasis on bringing other people to the faith) and origins (including separatist movements against established religious institutions). Churches in the mainline tradition, by contrast, share other doctrines (such as a less exclusionary view of salvation), practices (such as a strong emphasis on social reform) and origins. Churches in the historically black Protestant tradition have been shaped uniquely by the experiences of slavery and segregation, which put their religious beliefs and practices in a special context.

As much as possible, Protestant respondents were categorized into one of the three Protestant traditions based not on their denominational family, but rather on the specific denomination with which they identify. Most Protestant denominational families include denominations that are associated with different Protestant traditions. For example, some Baptist denominations (like the Southern Baptist Convention) are part of the evangelical tradition; others (such as the American Baptist Churches USA) are part of the mainline tradition; and still others (such as the National Baptist Convention) are part of the historically black Protestant tradition.

Overall, 60% of Baptists in the survey identify with denominations in the evangelical tradition; 14% associate with denominations in the mainline Protestant tradition, and 26% identify with denominations that are part of the historically black Protestant tradition. (While the Baptist family of denominations includes churches in all three Protestant traditions, this is not the case for all denominational families, some of which have members in just one or two of the Protestant traditions.)

Despite the detailed denominational measures used in the Religious Landscape Study, many respondents (more than a quarter of all Protestants) were either unable or unwilling to describe their specific denominational affiliation. For instance, some respondents describe themselves as “just a Baptist” or “just a Methodist.” Respondents with this type of vague denominational affiliation were sorted into one of the three Protestant traditions in two ways.¹³

First, blacks who gave vague denominational affiliations (e.g., “just a Methodist”) but who said they belong to a Protestant family with a sizable number of historically black churches (including the Baptist, Methodist, nondenominational, Pentecostal and Holiness families) were coded as members of the historically black Protestant tradition. Black respondents in denominational families without a sizable number of churches in the historically black Protestant tradition were coded as members of the evangelical or mainline Protestant traditions depending on their response to a separate question asking whether they would identify as a born-again or evangelical Christian.

Second, non-black respondents who gave vague denominational identities and who described themselves as born-again or evangelical Christians were coded as members of the evangelical tradition; otherwise, they were coded as members of the mainline tradition.¹⁴

Overall, 38% of Protestants offered a vague denominational identity and thus were classified on the basis of their race and/or their answer to the question about whether they identify as a born-again or evangelical Christian. This includes 36% of those in the evangelical tradition, 35% of those in the mainline tradition and 53% of those in the historically black Protestant tradition.

The Shifting Composition of American Protestantism

Recent years have brought a dramatic decline in the share of Americans who identify with mainline Protestant denominations. Today, just 15% of all U.S. adults identify with mainline Protestant churches, down from 18% in 2007. By comparison, evangelical Protestantism and the historically black Protestant tradition have been more stable. Today, 25% of U.S. adults identify with evangelical denominations, down less than one percentage point since 2007. And roughly 7% of American adults identify with the historically black Protestant tradition, little changed since 2007.

The mainline tradition’s share of the Protestant population has declined along with its share of the overall population. Today, 32% of Protestants identify with denominations in the mainline tradition, down from 35% in 2007. Evangelicals now constitute a clear majority of all Protestants in the U.S., with their share of the Protestant population having risen from 51% in 2007 to 55% in 2014.

Many Protestant denominational families have seen their share of the U.S. population fall since 2007. Baptists now account for approximately 15% of the adult population, down from 17% in 2007. Methodists and Lutherans also have declined by more than a full percentage point in recent years. The family that shows the most significant growth is the nondenominational family; today, 6.2% of all adults (and 13% of Protestants) identify with nondenominational churches, up from 4.5% of all adults (and 9% of all Protestants) in 2007.

The Southern Baptist Convention (an evangelical denomination) and the United Methodist Church (a mainline denomination) continue to be the two largest Protestant denominations in the U.S.; 11% of Protestants identify with the Southern Baptist Convention and 8% identify with the United Methodist Church. Both denominations, however, have experienced declines in their relative share of the population. In the 2014 Religious Landscape Study, 5.3% of all U.S. adults identify with the Southern Baptist Convention (down from 6.7% in 2007) and 3.6% identify with the United Methodist Church (down from 5.1% in 2007).

Growth of Non-Christian Faiths

The 2014 Religious Landscape Study finds that 5.9% of U.S. adults identify with faiths other than Christianity, up slightly, but significantly, from 4.7% in 2007. The largest of these faiths is Judaism, with 1.9% of respondents identifying themselves as Jewish when asked about their religion. Among Jews surveyed, 44% identify with Reform Judaism, 22% with Conservative Judaism, 14% with Orthodox Judaism, 5% with other Jewish movements and 16% with no particular Jewish denomination. These findings are broadly similar to results from the Pew Research Center’s 2013 survey of Jewish Americans.¹⁵

Muslims (0.9%), Buddhists (0.7%) and Hindus (0.7%) each make up slightly less than 1% of respondents in the 2014 Religious Landscape Study. The Muslim and Hindu shares of the population have risen significantly since 2007. And it is possible, even despite this growth, that the Religious Landscape Study may underestimate the size of these groups. The study was conducted in English and Spanish, which means that groups with above-average numbers of people who do not speak English or Spanish (such as immigrants from Asia, Africa and other parts of the world) may be underrepresented. For instance, an analysis of the Pew Research Center’s 2012 survey of Asian Americans (conducted in English, Cantonese, Hindi, Japanese, Korean, Mandarin, Tagalog and Vietnamese) estimated that Buddhists account for between 1.0% and 1.3% of the U.S. adult population, and that Hindus account for between 0.5% and 0.8% of the population. The Pew Research Center’s 2007 and 2011 surveys of Muslim Americans (conducted in English, Arabic, Farsi and Urdu) estimated that Muslims accounted for 0.6% of the adult population in 2007 and 0.8% in 2011.

The 2014 Religious Landscape Study finds that 0.3% of American adults identify with a wide variety of other world religions, including Sikhs, Baha’is, Taoists, Jains, Rastafarians, Zoroastrians, Confucians and Druze. An additional 1.5% identify with other faiths, including Unitarians, those who identify with Native American religions, Pagans, Wiccans, New Agers, deists, Scientologists, pantheists, polytheists, Satanists and Druids, to name just a few.

Atheists and Agnostics Make Up a Growing Share of the Unaffiliated

The religiously unaffiliated population – including all of its constituent subgroups – has grown rapidly as a share of the overall U.S. population. The share of self-identified atheists has nearly doubled in size since 2007, from 1.6% to 3.1%. Agnostics have grown from 2.4% to 4.0%. And those who describe their religion as “nothing in particular” have swelled from 12.1% to 15.8% of the adult population since 2007. Overall, the religious “nones” have grown from 16.1% to 22.8% of the population in the past seven years.

As the unaffiliated have grown, the internal composition of the religious “nones” has changed. Most unaffiliated people continue to describe themselves as having no particular religion (rather than as being atheists or agnostics), but the “nones” appear to be growing more secular. Atheists and agnostics now account for 31% of all religious “nones,” up from 25% in 2007.

Meanwhile, the share of the “nones” describing their religion as “nothing in particular” has declined from 75% in 2007 to 69% in 2014. And this decline is especially notable among those who say religion is “very” or “somewhat” important in their lives despite eschewing any identification with a particular religion. Those who describe their religion as “nothing in particular” and who also say that religion is important in their lives now account for 30% of all religious “nones,” down from 36% in 2007. Those who describe their religion as “nothing in particular” and furthermore state that religion is unimportant in their lives account for 39% of all religious “nones,” the same share as 2007.

Like the 2007 Religious Landscape Study, the new survey shows a remarkable degree of churn in the U.S. religious landscape. If Protestantism is treated as a single religious group, then fully 34% of American adults currently have a religious identity different from the one in which they were raised, which is up six percentage points since 2007. If the three major Protestant traditions (evangelical Protestantism, mainline Protestantism and historically black Protestantism) are analyzed as separate categories, then the share of Americans who have switched religions rises to 42%.¹⁶ And these figures do not include an estimate of the number of “reverts” (people who leave their childhood religion before returning to it later in life). If the survey had measured this category, the estimates of the number of people who have switched religions would be higher still.

Along with other sources of change in the religious composition of the U.S. (like immigration and differential fertility or mortality rates), understanding patterns of religious switching is central to making sense of the trends observed in American religion. And perhaps the best way to assess the impact of switching on the composition of the U.S. religious landscape is to consider the ratio of the number of people who have joined each religious group to the number of people who have left. After all, every religious tradition ultimately loses some of the people who were raised within its fold, and every tradition (including the unaffiliated) gains some members who join its ranks after having been raised in a different group.

Looked at this way, the data clearly show that part of the reason the religious “nones” have grown rapidly in recent decades is that they continue to be the single biggest destination of movement across religious boundaries. Nearly one-in-five American adults (18%) were raised in a religion and are now unaffiliated, compared with just 4% who have moved in the other direction. In other words, for every person who has left the unaffiliated and now identifies with a religious group more than four people have joined the ranks of the religious “nones.”

By contrast, both Catholicism and mainline Protestantism, the two groups whose shares of the overall population have declined most sharply in recent years, have lost more members to religious switching than they have gained. Among U.S. adults, there are now more than six former Catholics (i.e., people who say they were raised Catholic but no longer identify as such) for every convert to Catholicism. And there are approximately 1.7 people who have left mainline Protestantism for every person who has joined a mainline denomination.

This chapter examines the religious groups that experience net gains and losses from changes in religious affiliation and documents the high degree of turnover among American religious groups. In addition, it analyzes the patterns of membership gain, loss and retention among religious groups.

The chapter also details the survey’s findings about interfaith marriage, which suggest that religious intermarriage is becoming more common. In fact, people who have gotten married since 2000 are about twice as likely to be in religious intermarriages as are people who got married before 1960.

Net Gains and Losses by Religious Tradition: Unaffiliated Make Big Gains, Catholics Suffer Major Losses

No religious group is only losing members or gaining members. Rather, each religious group is simultaneously gaining and losing members. Examining the total number of people entering and leaving each religion provides the most complete picture of the dynamism of the American religious landscape.

The group that has experienced the greatest net gains due to religious switching is the religiously unaffiliated. Fewer than one-in-ten adults (9.2%) say they were raised as religious “nones.” And nearly half of those who were raised unaffiliated (4.3% of all U.S. adults) now identify with a religion. But fully 18% of American adults were raised in a religious tradition and now describe themselves as unaffiliated. Currently, 22.8% of American adults identify as unaffiliated, which is nearly 14 percentage points higher than the share who say they were raised as religious “nones.”

In contrast with the unaffiliated, Catholicism has experienced the greatest net losses due to religious switching. Nearly a third of all U.S. adults (31.7%) were raised Catholic, and most of them continue to identify as Catholics today. But nearly 13% of all Americans are former Catholics – people who no longer identify with the faith despite having been raised in the Catholic Church. By comparison, there are far fewer converts to Catholicism; 2% of all U.S. adults now identify as Catholics after having been raised in another religion or without a religion. This means that there are more than six former Catholics for every convert to Catholicism. No other religious group analyzed in the survey has experienced anything close to this ratio of losses to gains via religious switching.

Mainline Protestantism also has lost more members than it has gained through religious switching. Overall, 10.4% of adults are former mainline Protestants, compared with 6.1% who now identify with mainline Protestantism after having been raised in another faith.

Driven primarily by the losses experienced by Catholicism and mainline Protestantism, Christianity as a whole loses more adherents than it gains via religious switching. The vast majority of U.S. adults (85.6%) say they were raised as Christians. But more than a fifth of them (19.2% of all adults) no longer identify with Christianity. Far fewer Americans (4.2% of all adults) have converted to Christianity after having been raised in another faith or with no religious affiliation. Overall, there are more than four former Christians for every convert to Christianity.

Within Christianity, the major exception to this pattern is evangelical Protestantism, which gains more adherents through religious switching than it loses. Overall, nearly a quarter of U.S. adults (23.9%) say they were raised as evangelical Protestants. More than a third of them (8.4% of all adults) no longer identify with evangelicalism. But even larger numbers (9.8% of all adults) now identify with evangelical Protestantism after having been raised outside the tradition.

Net Gains and Losses by Protestant Denominational Families: Gains for Nondenominational Protestants, Losses for Many Others

Many Protestant denominational families lose more people through religious switching than they gain. Nearly one-in-five American adults, for example, were raised Baptist (19.2%). But more than four-in-ten of them (8.4% of all U.S. adults) are no longer Baptist. Fewer people (4.5% of all adults) now identify as Baptist after having been raised in another religion, meaning that there are roughly two former Baptists for each person who has become a Baptist after having been raised in another religion or without a religion. The survey finds similar rates of losses to gains (roughly 2-to-1) for Methodists, Lutherans, Presbyterians, Episcopalians and Congregationalists.

Nondenominational Protestants, by contrast, gain more adherents through religious switching than they lose. Just 2% of Americans say they were raised as nondenominational Protestants, and half of them (1.1% of all adults) no longer identify with nondenominational Protestantism. But 5.3% of adults now identify as nondenominational Protestants after having been raised in another religion or in no religion, meaning that nondenominational Protestantism gains roughly five adherents through religious switching for every adherent it loses.

Retention of Childhood Members: Hindus, Muslims and Jews Most Successful at Retaining Adherents

Hindus, Muslims and Jews are the three religious traditions that retain the largest shares of the adherents raised within their group. Among all U.S. adults who say they were raised as Hindus, fully 80% continue to identify with Hinduism as adults; most of those who no longer identify as Hindus now describe themselves as unaffiliated. Roughly three-quarters of those raised as Muslims (77%) and Jews (75%) also continue to identify with their childhood faiths.

Among Christian groups, the historically black Protestant tradition retains the highest percentage of its childhood members, followed by evangelical Protestants and Mormons. Seven-in-ten respondents who were raised within the historically black Protestant tradition continue to identify with it today, while roughly two-thirds of those raised as evangelicals (65%) and Mormons (64%) continue to identify with their childhood faiths. Among those who have left the historically black Protestant and evangelical traditions, there are more people who now identify with other religions than who identify with no religion. By contrast, most former Mormons (21% of all adults who were raised as Mormons) now say they have no religious affiliation.

Catholicism’s retention rate has slipped since the first Religious Landscape Study was conducted in 2007. At that time, 68% of respondents who were raised Catholic continued to identify as such as adults. Today, 59% of those raised Catholic still identify with Catholicism as adults, while 41% do not. One-in-five people who were raised Catholic now say they have no religious affiliation, while 10% identify with evangelical denominations, 5% with mainline denominations and smaller numbers with other faiths.

Just over half of those who were raised with no religious affiliation (53%) still identify as religious “nones,” one of the lower retention rates among religious traditions. The low retention rate of the religiously unaffiliated may seem paradoxical, since they ultimately obtain bigger gains through religious switching than any other tradition. Despite the fact that nearly half of those raised unaffiliated wind up identifying with a religion as adults, “nones” are able to grow through religious switching because people switching into the unaffiliated category far outnumber those leaving the category. A quarter of those raised as mainline Protestants have become “nones,” along with 20% of those raised Catholic, 15% of those raised in the evangelical Protestant tradition and 13% of those raised in the historically black Protestant tradition.

The data show, furthermore, that the share of those raised as “nones” who remain unaffiliated as adults is growing. Compared with 2007, the retention rate of the religiously unaffiliated has increased by seven percentage points (from 46% to 53%). This is driven, in large part, by generational replacement; young adults who were raised as “nones” are far more likely than their counterparts in previous generations to continue to identify as unaffiliated. Fully two-thirds of Millennials who were raised unaffiliated continue to identify as “nones” as adults. In fact, “nones” have among the highest retention rates among Millennials, significantly higher than the comparable rates for those raised in the evangelical Protestant (61%), historically black Protestant (60%), Catholic (50%) and mainline Protestant (37%) traditions and about equal to the retention rate for Jews (70%). (The survey included too few interviews with people raised in other faiths to permit a similar analysis by generational cohort.) Among older generations, by contrast, far fewer people who were raised as religious “nones” remain religiously unaffiliated as adults.

Of course, it is possible that growing numbers of Millennials who were raised unaffiliated will begin to identify with a religion as they get older, settle down, get married and have children. However, previous research suggests that generational cohorts typically do not become more religiously affiliated as they get older. Indeed, the current study suggests that most generational cohorts are becoming less religiously affiliated as they age.

Retention Rates Among Protestant Denominational Families

The 2014 Religious Landscape Study finds that 57% of all adults who were raised as Baptists continue to identify as Baptists. Anabaptists (52%), Lutherans (51%), Adventists (51%) and Pentecostals (50%) retain the allegiance of about half of their childhood adherents. Many other Protestant denominational families have lower retention rates. Four-in-ten or fewer of those raised as Methodists (40%), Episcopalians (39%), Presbyterians (34%), Reformed Protestants (34%), Holiness Protestants (32%) and Congregationalists (31%) continue to identify with those denominational families as adults.

Significant minorities of those raised in nearly all Protestant denominational families now say they are unaffiliated, ranging from 15% among those raised Baptist, Pentecostal or Restorationist to 28% of those raised Congregationalist. The only exception to this pattern is the Anabaptist denominational family; just 5% of those raised Anabaptist now identify as religious “nones.”

Groups Most Heavily Composed of Religious Switchers

The flip side of examining retention rates (which show the groups that are most successful at holding on to those raised in their ranks) is to consider which groups are most heavily made up of people who have switched into the group.

Nearly eight-in-ten adults who currently identify as religious “nones” were raised in a religion, while just 21% were raised religiously unaffiliated. Among adults who currently have no religious affiliation, there are more former Catholics (28%) and about as many former mainline Protestants (21%) as there are people who were raised with no religious affiliation (21%).

Most people who currently identify as Jehovah’s Witnesses (65%) also were raised outside that tradition. And 67% of the Buddhists surveyed indicate that they were raised in a religion other than Buddhism or with no religious affiliation. However, since the survey was conducted only in English and Spanish, Buddhists who speak other languages (e.g., Vietnamese, Japanese or other Asian languages), and who are not comfortable taking a survey in either English or Spanish, are underrepresented. The Pew Research Center’s 2012 survey of Asian Americans indicates that most Asian-American Buddhists were raised as Buddhists.

At the other end of the spectrum, fully 90% of adult Catholics are “cradle Catholics” raised in the church. Similarly, 90% of Hindus say they were raised as Hindus.

Within Protestantism, roughly six-in-ten evangelical Protestants (61%) and mainline Protestants (58%) say they were raised within their respective traditions. Each group includes substantial minorities, however, who were raised in the other faith; 14% of current evangelical Protestants were raised in the mainline tradition, and 20% of mainline Protestants were raised in the evangelical tradition. Each group also includes sizable numbers of former Catholics, with 13% of current evangelical Protestants and 12% of current mainline Protestants indicating that they were raised Catholic. Compared with evangelicals and mainline Protestants, the historically black Protestant tradition includes fewer people who have switched in from a different religious background.

Interfaith Marriage Commonplace

Interfaith relationships are common among married people and those living with a romantic partner, and interfaith marriage appears to be on the rise. If Protestantism is treated as a single religious group, then 28% of American adults who are married or living with a partner have a spouse or partner with a religion different than their own. When the three major Protestant traditions (evangelical Protestantism, mainline Protestantism and historically black Protestantism) are analyzed as separate categories, the number rises to 33%.

Interfaith relationships are far more common among unmarried people who are living with a partner (49% of whom have a partner with a religion different from their own) than among married people (31% of whom are in a religiously mixed marriage). Even among married people, however, mixed-faith relationships appear to be growing more common. Nearly four-in-ten married people who were wed since 2010 have a spouse who identifies with a different religious group (including Protestants who are married to a spouse from a different Protestant tradition). By contrast, just 19% of people who got married before 1960 have a spouse with a different religion.¹⁷

These patterns strongly suggest that intermarriage has been rising, but it also should be noted that some research indicates that “in-marriages” (marriages between people of the same religion) tend to be more durable than intermarriages.¹⁸ The Religious Landscape Study does not measure whether couples were in religiously mixed marriages at the time they got married; these marriages would no longer be counted as interfaith relationships if one or both spouses switched religions and they now share the same faith. If it were possible to analyze these other types of mixed marriages (i.e., those that ended in divorce and those that now are religiously matched marriages due to religious switching), then the percentage of intermarriages in previous decades may have been higher than it appears because the study only looks at marriages that are intact today.

The apparent rise of religious intermarriage is driven in large part by marriages between Christians and religiously unaffiliated spouses. Fully 18% of people surveyed who have gotten married since 2010 are either Christians with a religiously unaffiliated spouse or religious “nones” with a Christian spouse, as are 16% of people who got married between 2000 and 2009. By comparison, just 5% of people surveyed who got married before 1960 fit this profile. The rates of intra-Christian mixed marriage (e.g., between an evangelical Protestant and a mainline Protestant, or between a Catholic and a Mormon) are closer among those who got married recently and those who have been married for a long time.

Among those surveyed who are married or living with a partner, Buddhists are more likely than members of most other groups to indicate that they are in a mixed-faith relationship, with fully six-in-ten Buddhists (61%) saying their spouse or partner has a religion other than Buddhism. However, Asian-American Buddhists are underrepresented in the study because the survey was conducted only in English and Spanish and not in Asian languages such as Japanese, Mandarin or Vietnamese. In the current study, just 33% of Buddhists identify their race as Asian American. But the Pew Research Center’s 2012 survey of Asian Americans (conducted in English and seven Asian languages) found that roughly two-thirds of all U.S. Buddhists are Asian Americans, and that most married Asian-American Buddhists are married to a spouse who is also Buddhist. Thus, the 2014 Religious Landscape Study’s estimated intermarriage rate for Buddhists is likely much higher than it would have been had the survey been offered in Asian languages (and included more Asian-American Buddhists).

Hindus are more likely than any other religious group to have a spouse or partner with the same religion (91%). Roughly eight-in-ten Mormons (82%) and Muslims (79%) who are married or living with a partner have a mate who shares their religion, as do three-quarters of Catholics and evangelical Protestants.

The U.S. population is undergoing a variety of demographic changes. For example, racial and ethnic diversity has been increasing as non-Hispanic whites have declined as a share of the population. And the share of adults who are married has been declining for decades. These broader changes are reflected within many of the major religious groups in the U.S. Since 2007, most religious groups have exhibited a decline in the non-Hispanic white share of their populations and a rise in the Hispanic share. And marriage rates are down among several religious groups.

Nonetheless, there is some variation among religious groups in the direction and magnitude of demographic changes. For instance, while the evangelical and mainline Protestant traditions have become somewhat more racially diverse, the share of Mormons who are non-Hispanic whites has hardly budged. Hispanics constitute a greater share of the Catholic population than of any other religious group; fully one-third of U.S. Catholic adults are Hispanics.

The data also show that religious groups that are growing tend to be younger than average and getting younger, while religious groups that are shrinking tend to be relatively old and getting older.

This chapter provides a detailed account of the demographic composition of religious groups in the U.S., highlighting both how religious groups are changing demographically and how they are staying the same. The next chapter examines demographics and religion from the opposite direction, describing the religious composition of various social and demographic groups.

Age Differences Among Religious Groups

The religious groups that are growing tend to be relatively young and getting younger, whereas the religious groups that are shrinking tend to be relatively old and getting older. The median age of religiously unaffiliated adults, for example, now stands at 36, down from 38 in 2007. Among self-identified atheists and agnostics, the median age is 34, and roughly four-in-ten adults in these categories are between the ages of 18 and 29. Muslims and Hindus also stand out for their comparative youthfulness; the median age of adults in each group is 33.

By contrast, the median age of Christian adults is 49, up from 46 in 2007. One-in-five Christians (21%) have reached the traditional retirement age of 65, compared with just 9% of the religiously unaffiliated, 5% of Muslims and 4% of Hindus.

Jews have a median age of 50, the same as in 2007 and on par with Catholics and Protestants as a whole.

Race and Ethnicity of Religious Groups

As the United States has become more racially and ethnically diverse in recent years – with fewer whites (as a share of the population) and more Hispanics and other racial and ethnic minorities – so, too, have the racial and ethnic profiles of many religious groups become more diverse. Whites now account for smaller shares of the evangelical, mainline Protestant, Catholic and religiously unaffiliated populations than they did in 2007, while Hispanics have grown as a share of all of these groups.

Hispanics make up a larger share of the U.S. Catholic population than they do of almost any other religious group. About one-third of Catholics are Hispanic (34%), up from 29% in 2007. And the data suggest that the Hispanic share of the Catholic population is likely to continue to grow at a rapid pace, since Hispanic Catholics are far younger, on average, than non-Hispanic Catholics. The median age of Hispanic Catholic adults is 42, while the median age of non-Hispanic Catholics is 53. And among Catholic Millennials, there are about as many Hispanics as whites. Among older generations of Catholics, there are more whites than Hispanics.¹⁹

Several religious traditions, including the historically black Protestant tradition, Jehovah’s Witnesses, Muslims, Buddhists and Hindus, are composed mostly of racial and ethnic minorities.

Two-thirds of religiously unaffiliated adults are white. This includes more than three-quarters of self-identified atheists (78%) and agnostics (79%), as well as 72% of those who say their religion is “nothing in particular” and who further state that religion is unimportant in their lives. By comparison, those who describe their religion as “nothing in particular” but who say religion is at least somewhat important in their lives are much more racially diverse.

Religion and Immigration

Fully 96% of Hindus in the U.S. are either immigrants (87%) or the children of immigrants (9%), as are nearly eight-in-ten Muslims (61% immigrants and 17% the children of immigrants). The vast majority of Hindus in the U.S. – 78% – were born in the Asia-Pacific region (India is home to by far the world’s largest Hindu population). Muslim immigrants come from many places around the world, including 27% who were born in the Asia-Pacific region, 12% who were born in the Middle East and North Africa and 12% who were born in sub-Saharan Africa.²⁰

Among Christian groups, the Orthodox tradition is most heavily made up of immigrants and the children of immigrants. Four-in-ten Orthodox Christians were born outside the U.S. (including 20% who were born in Europe, 7% who were born in sub-Saharan Africa and 7% who are from the Asia-Pacific region); 23% of Orthodox Christians are the children of immigrants. More than four-in-ten Catholics are either first-generation (27%) or second-generation (15%) Americans. Most Catholic immigrants were born in the Americas (including Latin America and the Caribbean, as well as Canada).²¹

Educational Attainment and Income of Religious Groups

Hindus and Jews continue to be among the most highly educated religious groups in the U.S., just as they were when the 2007 Religious Landscape Study was conducted. Most adults in each group have at least a bachelor’s degree (77% of Hindus and 59% of Jews). And nearly half of Hindus (48%) and one-third of Jews (31%) have earned a post-graduate degree.

U.S. Muslims, Buddhists and Orthodox Christians also have relatively high levels of educational attainment, with roughly four-in-ten or more in each group having completed college. Atheists and agnostics have high levels of education as well, with 43% of self-identified atheists and 42% of agnostics saying they have completed college. Others within the religiously unaffiliated category are not as highly educated; 30% of those who describe their religion as “nothing in particular” and say religion is unimportant in their lives report having attained a bachelor’s degree, along with 16% of those who say their religion is “nothing in particular” and that religion is at least somewhat important to them.

A quarter of Catholics have completed college (26%), as have a similar share of Protestants (24%). Mainline Protestants are much more likely than their counterparts in the evangelical and historically black Protestant traditions to have completed college.

Differences in income across religious traditions largely mirror the differences in educational attainment. Jews and Hindus are among the groups most likely to report an annual household income of $100,000 or more (44% of Jews and 36% of Hindus). By contrast, large shares of members of the historically black Protestant tradition (53%), Jehovah’s Witnesses (48%) and people who say their religion is “nothing in particular” but that religion is at least somewhat important in their lives (47%) report household incomes of under $30,000 a year.

Catholics and Protestants overall largely mirror the U.S. general public in their income levels, though Protestants in the mainline tradition are somewhat more well-off by this measure than are their counterparts in the evangelical and historically black Protestant traditions.

Atheists and agnostics tend to be relatively wealthy, with about six-in-ten in each group making $50,000 or more per year. By contrast, those who describe their religion as “nothing in particular” and who say religion is unimportant to them closely mirror the population as a whole, while those who say their religion is “nothing in particular” but that religion is at least somewhat important to them tend to have below-average family incomes.

Gender Composition of Religious Groups

As in 2007, women continue to make up more than half of nearly every Christian group. Roughly two-thirds of Jehovah’s Witnesses are women, as are 59% of those who identify with the historically black Protestant tradition, 55% of those in both the evangelical and mainline Protestant traditions and 54% of Catholics and Mormons.

Most religiously unaffiliated adults, by contrast, are men. Fully two-thirds of self-identified atheists are men, as are 62% of agnostics and 55% of those who identify religiously as “nothing in particular” and further say that religion is unimportant in their lives. Among those who describe their religion as “nothing in particular” but say that religion is at least somewhat important in their lives, however, there are about as many women as men.

Marital Status and Family Size of Religious Groups

Since the first Religious Landscape Study was conducted in 2007, the share of Americans who are married has continued to decline, while the share of adults who have never been married has risen sharply. In fact, recent analysis of census data shows that the share of Americans who have never been married now stands at an all-time high.

These trends are evident across several religious groups. The share of evangelical Protestants, Catholics and religiously unaffiliated respondents who are married declined noticeably between 2007 and 2014.

Mormons continue to be among the groups most likely to be married. Compared with most other religious groups, there are fewer married people in the historically black Protestant tradition and among the religiously unaffiliated.

Just as they are more likely than people in most other faiths to be married, Mormons also tend to have larger families than do people in other religious groups. Mormons between the ages of 40 and 59 have had an average of 3.4 children over the course of their lives, significantly above the national average of 2.1 children. Mormons also report that they are currently raising more children than are members of most other religious groups. On average, Mormon adults of all ages report that they are now living with 1.1 children to whom they are parent or guardian.²²

By contrast, the unaffiliated tend to have smaller families than other groups. Religious “nones” between the ages of 40 and 59 have had an average of 1.7 children during their lives. Atheists have had an average of 1.6 children, and agnostics have had 1.3 children. Mainline Protestants also have below-average fertility rates.

Regional Distribution of Religious Groups

Some religious groups are disproportionately concentrated in certain areas of the country, while others tend to be more evenly distributed across geographic regions. Large shares of Protestants in all three major traditions live in the South, including a majority of those in the historically black Protestant tradition (62%), about half of evangelicals (49%) and a plurality of mainline Protestants (37%). A plurality of Jews live in the Northeast (42%).

Mormons are heavily concentrated in the West, though the share of Mormons in the current survey who reside in the West is down somewhat since 2007 (from 76% to 67%). The change, however, does not seem to be the result of large-scale movement of Mormons from the West to other regions. In fact, Mormons are virtually unchanged since 2007 as a share of the population in the Northeast, Midwest and South. Rather, the change is produced by a slight decline in the share of Westerners who identify as Mormons, from just under 6% in 2007 to just under 5% in 2014. Even such a small decline can result in a large change in the geographic distribution of a relatively small religious group, especially one that is heavily concentrated in a single geographic region. Future surveys will determine whether this small decline in the Mormon share of the Western population is the beginning of a trend or merely an outlier.

Compared with some other religious groups, Catholics are more evenly dispersed throughout the country, with about one-in-five living in the Midwest (21%) and a quarter or more in the Northeast (26%), South (27%) and West (26%). The geographic center of Catholicism is shifting gradually from the Northeast and Midwest toward the South and West. In 2007, a slim majority of Catholics (53%) resided in the Northeast or Midwest. Today, a slim majority of Catholics live in the South or West (52%). This shift is being driven by the continuing growth of Hispanics as a share of the U.S. Catholic population; three-quarters of Hispanic Catholics reside in the South or West, while six-in-ten non-Hispanic Catholics live in the Northeast or Midwest.

Previous research has shown clear differences in the religious identity, beliefs and practices of people from different demographic groups. Young adults tend to be less religiously affiliated than older people. Women tend to be more religiously affiliated than men. There are far more Catholics among Latinos than among people from other racial and ethnic backgrounds. Unmarried people are much more likely than those who are married to be unaffiliated with a religion. And the Western region of the U.S. is home to many more unaffiliated people than are other geographic regions.

The 2014 Religious Landscape Study finds that all of these demographic differences remain visible in the U.S. today. Older people still identify with religious groups at a higher rate than younger people. Women still are more religiously affiliated than men. And married people are far more likely than single people to identify with a religion.

But the new study also finds that the major shifts underway in American religion are occurring across a wide variety of demographic groups. Whether they are nearing retirement or just entering adulthood, married or single, living in the West or the Bible Belt, Americans in virtually all demographic groups are significantly less likely to describe themselves as Christians and more likely to identify as religious “nones,” compared with seven years ago.

This chapter takes a detailed look at the religious composition of demographic groups in the U.S., highlighting the differences that continue to exist among people from various backgrounds, as well as the similar changes that are afoot among many demographic groups. The previous chapter assesses the same data from the opposite direction, examining the demographic composition of religious groups.

Religious Composition by Generational Cohort

More than a third of adults in the Millennial generation (35%) now say they have no religion, up 10 points from 2007. Millennials have become more unaffiliated, both because large numbers of younger Millennials are entering adulthood with high levels of religious disaffiliation – 36% of those currently ages 18-24 are unaffiliated – and because older Millennials increasingly identify as religious “nones.” Roughly a third (34%) of older Millennials (now ages 25-33) identify as unaffiliated, up from 25% among this same cohort in 2007 (when they were 18-26). Just 56% of Millennial adults identify themselves as Christians, including 21% who identify with evangelical Protestantism, 16% with Catholicism and 11% with mainline Protestantism. By comparison, people in older generations are far more likely than Millennials to describe themselves as Christians and less likely to identify as religious “nones.”

But even older generations are growing less Christian over time. The share of people in Generation X who describe themselves as Christians, for instance, has dropped from 76% in 2007 to 70% today, while the unaffiliated share of Generation X has grown from 19% to 23%. The share of Christians among Baby Boomers and the Silent generation also ticked down slightly but noticeably in recent years, while the share of “nones” in these cohorts grew slightly.

Religious Composition of Racial and Ethnic Groups

The unaffiliated have grown and Christians have declined as a share of all racial and ethnic groups. Whites, however, continue to be more likely than both blacks and Hispanics to say they have no religion (24% among whites compared with 20% among Hispanics and 18% among blacks).

Blacks stand out for their high levels of identification with Protestantism (71%), especially with denominations in the historically black Protestant tradition (53%). Hispanics continue to identify with Catholicism in larger numbers than other racial and ethnic groups. However, the Catholic share of the Hispanic population has declined dramatically in recent years, from 58% in the 2007 Religious Landscape Study to 48% today.

Among people from other racial and ethnic backgrounds (e.g., those who are Asian, Native American or mixed race, but not Hispanic), fully one-in-five (21%) identify with non-Christian faiths, including 8% who describe themselves as Hindus, 4% as Buddhists and 3% as Muslims.

Religious Composition of Immigrants

Roughly seven-in-ten U.S.-born adults identify themselves as Christians (71%), as do 68% of immigrants. The Christian share of each group, however, has slipped in recent years (by eight percentage points among the native born and seven points among immigrants), while the unaffiliated share has grown.

Among the native born, most Christians (50% of all native-born adults) continue to identify with Protestantism; most Christian immigrants (39% of all of those born outside the U.S.) identify as Catholics.

Compared with immigrants who have been in the United States for decades (i.e., since before 1990), immigrants who have arrived more recently are somewhat less likely to be Christian and more likely to identify with non-Christian faiths or with no religion. Three-quarters of immigrants who arrived in the U.S. before 1990 identify with Christianity, compared with 64% of those who arrived in the 1990s and 63% of those who arrived since 2000. More than one-in-five immigrants who came to the U.S. in 1990 or later are unaffiliated, and 14% identify with non-Christian faiths such as Islam or Hinduism.

Religious Composition by Educational Attainment

The share of Christians has declined since 2007 among both college graduates (by nine percentage points) and those with less than a college degree (by eight points), while the unaffiliated share has grown among both groups (by seven points among college graduates and six points among those with less education).

Roughly a quarter of college graduates describe themselves as religious “nones,” as do 22% of those with less than a college education. College graduates, however, are nearly twice as likely as those with less education to identity as atheist or agnostic (11% vs. 6%). College graduates also are significantly more likely than those with less education to identify with non-Christian faiths such as Judaism or Hinduism (11% vs. 4%).

Religious Composition by Income Level

Compared with 2007, there are smaller shares of self-identified Christians and more religious “nones” among Americans in every household income bracket, from those earning less than $30,000 per year to those earning $100,000 or more. As of 2014, the religiously unaffiliated make up a fifth or more of each income bracket, from 22% of those making less than $30,000 each year to 26% of those earning $100,000 or more annually. Compared with those at the low end of the income scale, those at the very top (i.e., people with household incomes of at least $100,000) are somewhat less likely to describe themselves as Christians and more likely to identify with non-Christian faiths or to be unaffiliated.

Religious Composition by Gender

Women are far more likely than men to identify with Christian groups (75% vs. 66%). Men, by contrast, are more likely than women to describe themselves as religious “nones” (27% vs. 19%).

But both men and women have become less Christian and more unaffiliated since 2007, by roughly equal amounts. The share of men who identify with Christianity has shrunk by eight percentage points since 2007, and the share of self-identified Christians among women has declined by seven points. Meanwhile, the share of “nones” is up seven points among men and six points among women.

Religious Composition by Marital Status

Scholars have long recognized that religion and marriage are linked in important ways, with married people tending to be more religiously active than unmarried people. Princeton University sociologist Robert Wuthnow, for instance, has charted an overall decline in church attendance since the 1970s and attributes it to broader social trends like the postponement of marriage and parenthood by many young adults.²³ And the rise of the religious “nones” in recent decades has coincided with a decline in marriage rates, with recent census data showing that the marriage rate in the U.S. now stands at a record low.

The 2014 Religious Landscape Study finds that unmarried people are far more likely than those who are married to be unaffiliated. It also shows, however, that both groups – those who are married and those who are not – have grown less religiously affiliated in recent years, though married people have done so more slowly. Among married adults, 18% now describe themselves as religious “nones,” up four points since 2007. More than a quarter of unmarried adults (28%) have no religious affiliation, up nine points in recent years.

Within the broader category of unmarried U.S. adults, the growth of the religiously unaffiliated is especially evident among those who are living with a partner (26% were unaffiliated in 2007, compared with 35% today) and those who say they have never been married (24% vs. 34%). Both of these groups consist mostly of young people. Those who are divorced or separated and those who are widowed, two groups that consist mainly of older adults, have seen more modest increases in their shares of religious “nones.”²⁴

Religious Composition of Geographic Regions

As in 2007, the South continues to be the most heavily Christian region of the country; three-quarters of Southerners describe themselves as Christians, including 34% who identify with evangelical denominations. The Northeast is home to a greater share of Catholics than any other region (30%). And the West continues to have the largest share of people who are unaffiliated with any religion (28%).

Those three geographic regions, as well as the Midwest, all have experienced a decline in the share of Christians and a rise in the religiously unaffiliated since 2007. Perhaps the most dramatic changes have taken place in the Northeast, where the share of Christians overall is down 11 points (from 76% in 2007 to 65% today) and the share of Catholics is down seven points, from 37% to 30%. In the West, the unaffiliated now constitute the single largest tradition; 28% of those residing in the West are religiously unaffiliated, compared with 23% who are Catholics, 22% who are evangelical Protestants and 11% who identify with mainline Protestant denominations. Even the South has seen a six-point increase in the share of residents who are unaffiliated, from 13% in 2007 to 19% in 2014.

The Religious Landscape Study was designed to paint a religious portrait not just of the four major geographic regions, but also of every state and of the country’s largest metropolitan areas. Estimates of the composition of states and metro areas are available in the detailed tables in Appendix D as well as in the Religious Landscape Study interactive tool.

Religious Composition by Sexual Orientation

Among respondents who identify themselves as gay, lesbian or bisexual, fully 41% are religiously unaffiliated, and fewer than half (48%) describe themselves as Christians. Non-Christian faiths also are represented in the gay community at higher rates than among the general public, with 11% of gay, lesbian and bisexual respondents identifying with faiths other than Christianity.

These findings are broadly similar to results from the Pew Research Center’s 2013 survey of LGBT Americans. Different survey modes (the 2013 study was a self-administered survey whereas the 2014 Religious Landscape Study is an interviewer-administered survey) and questions used to identify gay, lesbian or bisexual respondents may explain small differences between the two surveys’ findings.

The centerpiece of Pew Research Center’s 2014 Religious Landscape Study is a nationally representative telephone survey conducted June 4-Sept. 30, 2014, among a sample of 35,071 U.S. adults. Approximately 60% of the interviews were conducted with respondents reached on cellphones (n=21,160) and 40% were completed on landlines (n=13,911). A minimum of 300 interviews were conducted in every state and the District of Columbia. Interviewing was conducted in English and Spanish. The survey is estimated to cover 97% of the non-institutionalized U.S. adult population; 3% of U.S. adults are not reachable by telephone or do not speak English or Spanish well enough to participate in the survey. No adjustments have been made to the survey’s estimates of the religious composition of the U.S. population to attempt to account for the small amount of non-coverage.

Data collection was divided equally among three research firms – Abt SRBI, Princeton Survey Research Associates International (PSRAI) and Social Science Research Solutions (SSRS). Abt SRBI served as the lead research firm coordinating the data collection, providing the sampling plan and producing the survey weights. Both the landline and cellphone samples were provided by Marketing Systems Group (MSG).

The size of the national sample is unusually large for a religion survey. There are two main reasons for this. First, the large sample size makes it possible to estimate the religious composition of the U.S. with a high degree of precision. After taking into account the survey’s design effect (based on the sample design and the survey weights), the margin of error for results based on the full sample is +/- 0.6 percentage points.

Second, the large sample size makes it possible to describe the demographic characteristics of a wide variety of religious groups, including relatively small groups that cannot be analyzed using data from smaller surveys. With more than 35,000 respondents in total, the Religious Landscape Study includes interviews with roughly 350 people in religious groups that account for just 1% of the U.S. population, and with 100 or more people in religious groups that are as small as three-tenths of 1% of the overall population. For instance, the study includes interviews with 245 Jehovah’s Witnesses, a group that accounts for less than 1% of the U.S. population and is typically represented by only a few dozen respondents in smaller surveys.

Sample Design

The national survey employed a dual-frame (cellphone and landline) random-digit dialing (RDD) approach to yield a nationally representative sample that included a minimum of 300 completed interviews in every state. This was accomplished by first allocating the total expected number of interviews (~35,000) to states in proportion to their respective share of the national adult population. At this stage, 16 states (including the District of Columbia) were identified in which the proportional allocation would result in fewer than 300 interviews. These 16 states were oversampled to obtain at least 300 interviews in each of them, while the remaining 35 states were undersampled proportionately. The weighting of the data (described below) ensures that all states are represented in their proper proportion in the national weighted estimates.

The allocation of sample to the landline or cellphone RDD frame was customized for each state to reflect state-level variation in telephone usage. The amount of sample allocated to cellphone numbers ranged from a low of 35% in Rhode Island to a high of 84% in Mississippi.

The landline sample was drawn from MSG’s 1+ assignment-assisted RDD sampling frame. The cellphone sample was also drawn by MSG, using their Cell-WINS activity flags. The Cell-WINS service appends activity code information to each sampled record, flagging it as active, inactive or “unknown.” In the initial cell sample, 59% of numbers were flagged as active, 40% were flagged as inactive and 1% were flagged as unknown. The cell sample was managed such that active and “unknown” numbers were oversampled while inactive numbers were undersampled. Oversampling cellphone numbers flagged as active or “unknown” helps to control survey costs by increasing the amount of interviewer time spent dialing eligible numbers. Retaining some numbers flagged as inactive ensures that the survey’s coverage rate was not affected. The weighting of the data corrects for the undersampling of flagged-inactive numbers so that they are represented in their proper proportion in the weighted estimates.

Interviewing

Sampled telephone numbers were called as many as seven times in an effort to obtain a completed interview. Numbers flagged as “callbacks” (i.e., numbers at which a respondent had begun the interview without completing the survey) were called back an additional two times during the final four weeks of the survey period. Refusal conversion was attempted in instances of soft refusals in both the landline and cellphone frames. Calls were staggered over times of day and days of the week to maximize the chance of making contact with potential respondents. Each number received at least one daytime call.

In the landline sample, interviewers asked to speak with the youngest adult at home at the time of the call. In the cellphone sample, interviews were conducted with the person who answered the phone provided the person was age 18 or older. Respondents reached on cellphones were offered a reimbursement of $5 for their cellphone minutes used participating in the survey.

In an effort to maximize the number of interviews with adults who primarily speak Spanish, the study utilized a special protocol in which sampled telephone numbers that service areas with sizable Hispanic populations were dialed by bilingual Spanish- and English-speaking interviewers. Two flags were created in each frame (landline and cellphone) to identify cases with a relatively high probability of requiring Spanish administration. In the landline RDD sample, the first flag identified telephone exchanges with an estimated Hispanic incidence of 65% or higher. In the cell frame, the first flag identified numbers that belonged to rate centers (i.e., billing centers) with an estimated Hispanic incidence of 70% or higher. These numbers were dialed exclusively by bilingual interviewers capable of conducting the interview in either English or Spanish. There was just one exception to this rule; respondents who completed part of the interview but did not finish the survey and who spoke English were eligible to be called back subsequently by interviewers who spoke only English.

Each frame (landline and cellphone) also included a second Hispanic incidence flag. The second flag in the landline sample identified exchanges with an estimated Hispanic incidence of 60% to 64.99%. The second flag in the cell frame identified numbers associated with rate centers with an estimated Hispanic incidence of 65% to 69.99%. In the event that the research firms that conducted the interviewing had bilingual interviewing capacity over and above that needed to dial numbers associated with the first flag, bilingual interviewers were then assigned to numbers identified with the second flag.

Ultimately, 3.8% of all interviews were conducted in Spanish, including 4.6% in the cellphone sample and 2.5% in the landline frame.

Weighting

National- and State-Level Weighting

The national- and state-level results included in this report are based on weighted estimates. The weighting was conducted in two stages. The first stage in the weighting produced base weights that account for several factors, including: 1) the probability of selection of the telephone number, computed separately for each of 102 sampling strata defined by the cross-classification of sample frame (landline and cellphone) and state (including the District of Columbia); 2) the oversampling of “active” numbers in the cell frame; 3) the within-household selection of one respondent per household in the landline frame; and 4) the overlap between the cell and landline frames.

The second stage of the weighting calibrated the base-weighted data to demographic benchmarks for the population covered by the survey. This was performed via iterative proportional fitting (or “raking”). The raking procedure aligned survey respondents to population benchmarks on the following dimensions within each state:

• Gender by age
• Gender by education level
• Education level by age
• Race/ethnicity
• Telephone service
• Region of state (except for the District of Columbia)

Most of the demographic weighting parameters came from the Census Bureau’s 2012 American Community Survey (ACS) one-year estimates, which was the most current data source available at the time the data were weighted. The ACS parameters were calculated for adults ages 18 and older residing in households in each state, excluding those living in institutionalized group quarters. The telephone service parameter for each state was constructed from model-based estimates released by the National Center for Health Statistics (NCHS) National Health Interview Survey (NHIS) for the year 2012. Since the cellphone-only adult population has increased every year since 2012, these state-level estimates were updated using 2013 NCHS data to reflect regional trends. The region parameter was specific to each state and was computed based on the 2012 ACS five-year estimates for adults living in each county in the U.S.

The distribution of the raked weights was examined separately for each state, and customized trimming was performed at the state level to prevent individual interviews from having too much influence on the final results and to reduce the variance of the weights at the state level. Finally, the weights for each state were scaled to correct for the oversampling of smaller states and the corresponding undersampling of larger states. This ensures that all states are represented in their proper proportion in the weighted estimates included in this report.

Metropolitan Area Weighting

In addition to providing estimates for the nation as a whole and for all 50 states and the District of Columbia, the national survey obtained interviews from 250 or more respondents in 22 of the nation’s largest Metropolitan Statistical Areas (MSAs): Atlanta, Baltimore, Boston, Chicago, Dallas, Detroit, Houston, Los Angeles, Miami, Minneapolis, New York City, Philadelphia, Phoenix, Pittsburgh, Providence, Riverside (Calif.), St. Louis, San Diego, San Francisco, Seattle, Tampa and the Washington, D.C., metro area (including the District of Columbia as well as parts of Maryland, Virginia and West Virginia).

Some MSAs span multiple states, which necessitated weighting each MSA separately. Like the national- and state-level weights, each MSA weight was calculated in two stages, beginning with the same first-stage (base) weight as in the national- and state-level weights. In the second stage, the base weight was adjusted for each MSA via raking to align survey respondents to population benchmarks on the following dimensions within each MSA:

• Gender by age
• Gender by education level
• Education level by age
• Race/ethnicity
• Telephone service

The demographic weighting parameters came from an analysis of the Census Bureau’s 2012 ACS five-year estimates, which was the most current data source available at the time the survey data were weighted. The ACS parameters were calculated for adults ages 18 and older residing in households in each MSA, excluding those living in institutionalized group quarters. The telephone service parameter was constructed from sub-state-level estimates released by the NCHS for the year 2012. Since the cellphone-only adult population has increased every year since 2012, these sub-state-level estimates were updated using 2013 NCHS data to reflect national trends.

Design Effect and Margins of Error

Weighting and survey design features that depart from simple random sampling (e.g., the oversampling of less populous states) tend to result in a loss of precision in survey estimates. This loss of precision, known as the design effect, is incorporated in all margins of error, standard errors and tests of statistical significance included in this report.

Generally speaking, larger sample sizes are associated with smaller margins of sampling error, and smaller sample sizes are associated with larger margins of error. The margin of error for national estimates from this survey is +/- 0.6 percentage points. The margins of error for subgroups are larger. The accompanying tables present sample sizes and corresponding margins of error for the religious traditions discussed throughout much of this report, as well as for each state and the MSAs analyzed here and online. Sample sizes and margins of error for other groups are available upon request.

In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls. For example, in surveys like this one that are conducted in English and Spanish, estimates for religious groups with large numbers of people who speak other languages (e.g., Buddhists, Muslims and others) may be biased toward the English- and Spanish-speaking subsets of these populations.

In addition to reporting on the characteristics of religious traditions and the religious composition of states and localities, this report and the accompanying interactive tool provide details on many other groups (e.g., men and women, immigrants and those born in the U.S., adherents of specific denominations such as the United Methodist Church and the Church of the Nazarene, etc.). Sample sizes for these groups vary widely; the survey includes interviews with 17,514 men and 17,557 women, but just 101 respondents who identify with the Church of the Nazarene. Sample sizes and margins of error for groups included in the detailed tables of the second Landscape Study report, “U.S. Public Becoming Less Religious,” can be found within the detailed tables as an additional aid.

As an aid to help readers interpret the study’s findings, the accompanying table provides approximate margins of error for groups of varying sizes. The margin of error for results based on men (n=17,514), for example, is +/- 0.9 percentage points. By contrast, the margin of error for results based on those who identify with the Church of the Nazarene (n=101) is much larger (+/- 12 percentage points). Readers should always bear in mind the approximate margin of error for the group they are examining when making comparisons with other groups or assessing the significance of trends over time.

Sample Disposition and Response Rates

The table below reports the disposition of all sampled telephone numbers dialed for the survey. Overall, the response rate (AAPOR3) was 11.1% for the landline sample and 10.2% for the cell sample.

Comparisons Between 2007 and 2014

One key goal of the 2014 Religious Landscape Study is to make comparisons between the current study and the original Landscape Study conducted in 2007. As such, the 2014 study repeated many of the questions and retained many of the methodological features of the 2007 study. There are, however, a few differences between the two studies worth noting.

First, though the two studies employed the same questions to categorize respondents into religious traditions, there are a few small religious groups that are categorized differently in 2014 than in 2007. For example:

• Jains were counted as Hindus in 2007 but are included in the “other world religions” tradition in 2014. Jains account for less than one-tenth of 1% of 2014 respondents.
• Those identifying with the Self Realization Fellowship were included in the “other world religions” tradition in 2007 but are counted as Hindus in 2014. They account for less than one-tenth of 1% of 2014 respondents.
• Those identifying with the New Thought movement were included in the New Age family in the “other faiths” tradition in 2007. In 2014, they are included in the Metaphysical family in the “other Christian” tradition. They account for less than one-tenth of 1% of 2014 respondents.

These small changes have no substantive impact on the interpretation of trends between the 2007 and 2014 survey.

Second, the 2014 study was conducted in all 50 states and the District of Columbia. Though the 2007 study included follow-up surveys in Alaska and Hawaii, the national estimates from the 2007 survey are based on interviews conducted in the 48 continental states and the District of Columbia. Analysis of the data shows that this change has no substantive impact on the interpretation of trends between the 2007 and 2014 survey.

Third, the 2007 survey was conducted only on landlines, whereas the 2014 study was conducted on landlines and cellphones. In 2007, roughly 14% of U.S. adults were cellphone-only (i.e., reachable on a cellphone but not by a landline telephone), and landline-only surveys were still a viable means by which to survey a nationally representative sample of the population. By 2014, it was no longer possible to conduct nationally representative surveys using only landlines, as the cellphone-only share of the population had grown to 43%.²⁵

Though the 2007 survey was conducted only on landlines, it also included an experimental component in which 500 cellphone-only respondents were interviewed, facilitating a comparison of the 2007 estimates both with and without cellphones included. That analysis showed that estimates of the religious composition of the U.S. were the same when cellphones were included and when they were not. As a result, this change in methodology is not expected to have a meaningful impact on the interpretation of trends between the 2007 and 2014 survey.

Furthermore, Pew Research Center political polls have been conducted on landlines and cellphones since 2008. Those polls typically include one question about religious identity, and they show a similar pattern in recent years to that observed in the Religious Landscape Study, with more Americans identifying as religious “nones” and fewer identifying as Protestants and Catholics. See Appendix C of the first Landscape Study report, “America’s Changing Religious Landscape,” for more details.

Fourth, the 2014 Religious Landscape Study was intended to document the religious composition of each of the 50 states in addition to the nation as a whole. To accomplish this, the sampling plan was designed to achieve a minimum of 300 interviews in every state, and the data for each state were weighted to demographic benchmarks derived from the U.S. Census Bureau and other government sources. The state in which respondents reside is determined by their self-reported ZIP code. By contrast, the 2007 study was not designed to yield a minimum number of interviews in every state and the 2007 data were not weighted to state-level demographic benchmarks. And in the 2007 study (which was conducted only on landlines), the state in which respondents reside was determined by their telephone number. Despite these differences, analysis of the 2007 state-level data indicates that the 2014 state-level results can safely be compared to the 2007 study.²⁶ Information on the religious composition of each state (and major metropolitan areas) is available in the detailed tables in Appendix D of the first Landscape Study report, “America’s Changing Religious Landscape,” and online through a new interactive tool.

Fifth, in an effort to increase the number of interviews conducted with Orthodox Christians, Buddhists and Hindus, the 2007 study called back respondents from a previous study who identified with those groups. The 2014 study includes only respondents who were contacted for the first time as part of the 2014 Religious Landscape Study. As a result, trends among these groups should be interpreted with caution. Additionally, the data suggest that Asian Americans interviewed as part of this and other studies conducted in English and Spanish may include a disproportionately large number of young Asian-American adults. Those who are interested specifically in the religious beliefs and practices of Buddhists and Hindus should consult findings from Pew Research Center’s 2012 survey of Asian Americans, which was conducted in English as well as seven Asian languages and which includes interviews with more Asian-American Buddhists and Hindus than does the Landscape Study.

This section documents the composition of the three major Protestant traditions (evangelical Protestantism, mainline Protestantism and historically black Protestantism) as they have been defined in this report.²⁷

Protestants were grouped into religious traditions based on the specific denomination with which they identify. For instance, all members of the Southern Baptist Convention have been classified as members of the evangelical Protestant tradition, those who belong to the American Baptist Churches USA are classified as members of the mainline Protestant tradition and those who belong to the National Baptist Convention are classified as members of the historically black Protestant tradition.

Protestant respondents who gave a vague answer to denominational questions (e.g., “I am just a Baptist” or “I know I am Methodist but don’t know which specific Methodist denomination I belong to”) were placed into one of the three Protestant traditions based on their race and/or their response to a question that asked if they would describe themselves as a “born-again or evangelical Christian.” This means that some groups may appear within more than one tradition. For example, independent Baptists appear in both the evangelical Protestant tradition and the historically black Protestant tradition, and a respondent’s placement into one or the other depends on the race of the respondent. These cases are noted in the detailed summary at the end of this appendix.

Overall, 38% of Protestants (including 36% of evangelical Protestants, 35% of mainline Protestants and 53% of those in the historically black Protestant tradition) gave a vague denominational identity, necessitating the use of their race or their born-again status (or sometimes both) to categorize them into one of the three major Protestant traditions.

The table below estimates the size of the largest Protestant denominations and identifies the Protestant tradition to which each belongs. Note that many denominational families include denominations that are associated with more than one Protestant tradition. For example, Baptists are found within all three Protestant traditions, Pentecostals belong to either the evangelical or historically black Protestant tradition and Lutherans belong to either the evangelical or mainline tradition.

Detailed Summary of Protestant Denominations by Tradition and Family

The denominations listed below represent answers given by survey respondents. Some denominations were offered to respondents as explicit answer categories during the interview, while others were volunteered by respondents. Respondents who gave vague denominational affiliations were assigned to a religious tradition based on their race and/or their response to a question that asked whether they would describe themselves as a “born-again or evangelical Christian,” as noted in italics.

Evangelical Protestant Tradition

Baptist in the evangelical tradition

Southern Baptist Convention
Independent Baptist (if non-black)
Baptist Missionary Association (if non-black)
Baptist General Conference/Swedish Baptist
Conservative Baptist Association of America
Free Will Baptist
General Association of Regular Baptists
American Baptist Association
Baptist Bible Church, including Baptist Bible Fellowship (if non-black)
Primitive Baptist (if non-black)
Reformed Baptist (Calvinist)
Fundamentalist Baptist (if non-black)
Seventh Day Baptist
Baptist General Convention of Texas
North American Baptist
Full Gospel Baptist Association (if non-black)
Evangelical Baptist (if non-black)
United Baptist Church
Evangelical Free Baptist
Cowboy Church Baptist
Pentecostal Baptist (if non-black)
Traditional Baptist (if non-black)
Ethnic Baptist (if non-black and born again)
Baptist, not further specified (if non-black and born again)
Baptist, ambiguous affiliation (if non-black and born again)

Methodist in the evangelical tradition

Congregational Methodist
Evangelical Methodist
Independent Methodist (if non-black)
Churches of Christ in Christian Union
Southern Methodist Church
Other ethnic Methodist (if non-black and born again)
Methodist, ambiguous affiliation (if non-black and born again)
Methodist, not further specified (if non-black and born again)

Nondenominational in the evangelical tradition

Nondenominational evangelical
Nondenominational fundamentalist
Nondenominational charismatic
Interdenominational (if born again)
Community church (if born again)
Nondenominational Protestant
Nondenominational Christian
Federated or union church (if born again)
Association of Bridge Churches
Ethnic nondenominational (if non-black and born again)
Electronic ministries
Nondenominational, ambiguous affiliation (if non-black and born again)
Nondenominational, not further specified (if non-black and born again)

Lutheran in the evangelical tradition

Lutheran Church-Missouri Synod
Lutheran Church-Wisconsin Synod
Lutheran Brethren
Church of the Lutheran Confession
Free Lutheran
Apostolic Lutheran Church in America
Lutheran Congregations in Mission for Christ
North American Lutheran Church
Lutheran Church of the Reformation
Conservative Lutheran
Ethnic Lutheran (if born again)
Lutheran, ambiguous affiliation (if born again)
Lutheran, not further specified (if born again)

Presbyterian in the evangelical tradition

Presbyterian Church in America
Associate Reformed Presbyterian
Cumberland Presbyterian Church
Orthodox Presbyterian
Evangelical Presbyterian
Reformed Presbyterian
Congregational Presbyterian
Bible Presbyterian Church
Conservative Presbyterian Church
Independent Presbyterian
Covenant Presbyterian Church
ECO: A Covenant Order of Evangelical Presbyterians
Charismatic Presbyterian
Ethnic Presbyterian (if born again)
Presbyterian, ambiguous affiliation (if born again)
Presbyterian, not further specified (if born again)

Pentecostal in the evangelical tradition

Assemblies of God
Church of God (Cleveland, Tenn.)
Four Square Gospel (Four Square)
Pentecostal Church of God
Pentecostal Holiness Church
Church of God of the Apostolic Faith
Assembly of Christian Churches
Church of God of Prophecy
Vineyard Fellowship
Open Bible Standard Churches
Full Gospel (if non-black)
Calvary Chapel
Apostolic Pentecostal (if non-black)
Nondenominational, independent Pentecostal (if non-black)
Missionary Church
Elim Fellowship
International Pentecostal Church of Christ
Evangelical Pentecostal
Church of God of Kentucky
Charismatic (if non-black)
Home church (if non-black)
International Communion of the Charismatic Episcopal Church
Other ethnic Pentecostal (if non-black)
Electronic ministries (if non-black)
Pentecostal, ambiguous affiliation (if non-black)
Pentecostal, not further specified (if non-black)

Anglican/Episcopalian in the evangelical tradition

Anglican Orthodox Church
Evangelical Anglican/Episcopalian
Anglican/Episcopalian, ambiguous affiliation (if born again)
Anglican/Episcopalian, not further specified (if born again)

Restorationist in the evangelical tradition

Church of Christ
Christian Churches and Churches of Christ
Restorationist, ambiguous affiliation (if born again)
Restorationist, not further specified (if born again)

Congregational in the evangelical tradition

Conservative Congregational Christian
National Association of Congregational Christian Churches
Evangelical Congregational
Independent Congregational Church
Ethnic Congregationalist (if born again)
Congregationalist, ambiguous affiliation (if born again)
Congregationalist, not further specified (if born again)

Holiness in the evangelical tradition

Church of the Nazarene
Wesleyan Church
Free Methodist Church
Christian and Missionary Alliance
Church of God (Anderson, Ind.)
Salvation Army
Wesleyan Methodist Church
Pilgrim Holiness Church
Free Holiness Holiness, ambiguous affiliation (if non-black)
Holiness, not further specified (if non-black)

Reformed in the evangelical tradition

Christian Reformed Church
Sovereign Grace
Evangelical Reformed
Independent Reformed
Reformed Church in the United States (German Reformed)
Calvinist
Protestant Reformed Church
Reformed, ambiguous affiliation (if born again)
Reformed, not further specified (if born again)

Adventist in the evangelical tradition

Seventh-day Adventist
Advent Christian
Worldwide Church of God/Grace Communion International
Church of God General Conference
Church of God (Seventh-day)
United Church of God
Living Church of God

Anabaptist in the evangelical tradition

Grace Brethren Church
Brethren in Christ
Mennonite Brethren
Amish
United Brethren in Christ, United Brethren
Social Brethren
Brethren, not further specified (if born again)
Mennonite, not further specified
Anabaptist, not further specified (if born again)

Pietist in the evangelical tradition

Evangelical Covenant Church (covenant)
Evangelical Free Church (free church)

Other evangelical/fundamentalist

“Evangelical”
“Born again,” “Bible believers,” etc.
Evangelical Bible Church
Plymouth Brethren
Bible, Gospel, Missionary Churches
Fundamentalist, not further specified
“Charismatic,” “spirit filled”
Electronic ministries

Protestant non-specific in the evangelical tradition

Home church (if non-black and born again)
Mixed Protestants (if non-black and born again)
Other Protestant non-specific (if non-black and born again)

Mainline Protestant Tradition

Baptist in the mainline tradition

American Baptist Churches USA
Cooperative Baptist Fellowship; Baptist Alliance
Liberal/progressive/moderate Baptist
Ethnic Baptist (if non-black and not born again)
Baptist, not further specified (if non-black and not born again)
Baptist, ambiguous affiliation (if non-black and not born again)

Methodist in the mainline tradition

United Methodist Church
Evangelical United Brethren
Methodist Episcopal Church
Methodist Protestant Church
Other ethnic Methodist (if non-black and not born again)
Methodist, ambiguous affiliation (if non-black and not born again)
Methodist, not further specified (if non-black and not born again)

Nondenominational in the mainline tradition

Interdenominational (if not born again)
Community Church (if not born again)
Federated or union church (if not born again)
Emergent Church
Liberal/moderate nondenominational
Ethnic nondenominational (if non-black and not born again)
Nondenominational, ambiguous affiliation (if non-black and not born again) Nondenominational, not further specified (if non-black and not born again)

Lutheran in the mainline tradition

Evangelical Lutheran Church in America
American Lutheran Church/Lutheran Church in America
Ethnic Lutheran (if not born again)
Lutheran, ambiguous affiliation (if not born again)
Lutheran, not further specified (if not born again)

Presbyterian in the mainline tradition

Presbyterian Church (U.S.A.)
Scotch Presbyterian
United Presbyterian
Presbyterian Church of Canada
Southern Presbyterian; Presbyterian Church in the United States
Ethnic Presbyterian (if not born again)
Presbyterian, ambiguous affiliation (if not born again)
Presbyterian, not further specified (if not born again)

Anglican/Episcopalian in the mainline tradition

Episcopal Church
Anglican Church (Church of England)
Church of Ireland
Anglican/Episcopalian, ambiguous affiliation (if not born again)
Anglican/Episcopalian, not further specified (if not born again)

Restorationist in the mainline tradition

Disciples of Christ
Restorationist, ambiguous affiliation (if not born again)
Restorationist, not further specified (if not born again)

Congregational in the mainline tradition

United Church of Christ
Liberal/progressive Congregational
Ethnic Congregationalist (if not born again)
Congregationalist, ambiguous affiliation (if not born again)
Congregationalist, not further specified (if not born again)

Reformed in the mainline tradition

Reformed Church in America (Dutch Reformed)
Free Hungarian Reformed Church
Reformed, ambiguous affiliation (if not born again)
Reformed, not further specified (if not born again)

Anabaptist in the mainline tradition

Church of the Brethren
Moravian Church
Brethren, not further specified (if not born again)
Anabaptist, not further specified (if not born again)

Friends in the mainline tradition

Society of Friends
Friends/Quaker not further specified

Other/Protestant non-specific in the mainline tradition

Home church (if non-black and not born again)
Mixed Protestants (if non-black and not born again)
“Ecumenical”
United Church of Canada
Metropolitan Community Church
Other Protestant non-specific (if non-black and not born again)

Historically Black Protestant Tradition

Baptist in the historically black Protestant tradition

National Baptist Convention
Progressive Baptist Convention
International Baptist
Independent Baptist (if black)
Missionary Baptist (if black)
Baptist Bible Fellowship (if black)
Primitive Baptist (if black)
Full Gospel Baptist (if black)
Evangelical Baptist (if black)
Pentecostal Baptist (if black)
Traditional Baptist (if black)
Black Baptist
Other ethnic Baptist (if black)
Electronic Baptist ministries (if black)
Baptist, not further specified (if black)
Baptist, ambiguous affiliation (if black)

Methodist in the historically black Protestant tradition

African Methodist Episcopal
African Methodist Episcopal Zion
Christian Methodist Episcopal Church
Independent Methodist (if black)
Black Methodist
Methodist, ambiguous affiliation (if black)
Methodist, not further specified (if black)

Nondenominational in the historically black Protestant tradition

Black nondenominational
Other ethnic nondenominational (if black)
Nondenominational, ambiguous affiliation (if black)
Nondenominational, not further specified (if black)

Pentecostal in the historically black Protestant tradition

Church of God in Christ
United Pentecostal Church International
United House of Prayer for All People
Black Pentecostal
Apostolic Pentecostal (if black)
New Testament Church of God
Nondenominational, independent Pentecostal (if black)
Full Gospel (if black)
Deeper Life Bible Church/Deeper Christian Life Ministry
Other ethnic Pentecostal (if black)
Electronic ministries (if black)
Pentecostal, ambiguous affiliation (if black)
Pentecostal, not further specified (if black)

Holiness in the historically black Protestant tradition

Independent Holiness
Apostolic Holiness Church
Holiness Baptist
Fire Baptized Holiness Church of God
Church of the Living God
Black Holiness
Holiness, ambiguous affiliation (if black)
Holiness, not further specified (if black)

Protestant non-specific in the historically black Protestant tradition

Home church (if black)
Mixed Protestants (if black)
Other Protestant non-specific (if black)

The 2014 Religious Landscape Study has several unique strengths. Its large sample size (n=35,071) and detailed, branching set of questions about religious identity make it possible to estimate the size of a wide variety of religious groups with a high degree of precision. The large sample also makes it possible to describe the characteristics of smaller religious groups that account for less than 1% of the U.S. population, something not possible with smaller surveys. In addition, the methodological approach employed by the survey (with a minimum of 300 interviews in every state) allows for estimates of the religious makeup of all 50 states, the District of Columbia and the nation’s largest metropolitan areas.

But the Religious Landscape Study is not the only source of long-term data on the changing religious composition of the U.S. The General Social Survey (GSS), a project of the independent research organization NORC at the University of Chicago, has been conducted every year or two since 1972. Sample sizes for GSS surveys range from 1,372 to 4,510 and average about 2,000 per year. The Gallup Organization has been asking about religious identity even longer, and releases aggregated results based on the surveys it conducts each year. The American Religious Identification Surveys (ARIS) are large-scale studies undertaken in 1990 (n=113,713), 2001 (n=50,281) and 2008 (54,461). Media organizations like The Washington Post and ABC News regularly conduct polls about politics and current events that include questions about religious identity. Understanding how the findings of the Religious Landscape Study compare with these sources, and with results from ongoing polls conducted monthly by the Pew Research Center, may help to put the study’s findings into a broader context.

All major religion surveys find that the unaffiliated share of the U.S. population (the percentage of religious “nones”) is growing rapidly. In the 2014 GSS, for instance, 21% of adults said they have no religious affiliation, up from just 8% in 1990 and 5% in 1972, when the GSS was first conducted.²⁸ Gallup polls find fewer religious “nones” in recent surveys (16% in 2014), but they, too, find that this population has been growing.

The ARIS studies found that the religious “nones” grew from 8% of the adult population in 1990 to 15% in 2008. Polling done in 2012 and early 2013 by Social Science Research Solutions (SSRS) – which is the same research firm that conducted the interviewing for the ARIS studies – suggests that the unaffiliated share of the population continued to grow after the 2008 ARIS survey, and stood at 20% in 2012. Washington Post-ABC News surveys also show an upward trajectory for the “nones,” though their growth is less pronounced in Post-ABC surveys than in some other sources.

The Religious Landscape Study’s finding that 23% of adults are unaffiliated with a religion is very similar to results from Pew Research Center monthly polls, which put the figure at 21% for 2014 (and at 22% in the summer of 2014, when data collection for the Landscape Study was being conducted).

Different survey organizations employ different methods and ask differently worded questions about religious identity, which may account for some of the variability in estimates. But all find that the unaffiliated share of the population has been increasing over time.²⁹

The surveys also show that the Protestant share of the population is declining. The GSS finds that the Protestant share of the population fell from 62% in 1990 to 48% in 2014. The decline of Protestantism has been less steep in Gallup surveys, but they, too, find that Protestants now account for fewer than 50% of U.S. adults. ARIS and SSRS surveys suggest that Protestants declined from 60% of the population in 1990 to roughly 50% in 2012. In Washington Post-ABC News surveys, the Protestant share of the population fell from a high of 61% in 2003 to 54% in 2014. And the trajectory for Protestants in the Religious Landscape Studies closely matches that seen in the Pew Research Center’s monthly polling.

There is less consensus about the trend for the Catholic population. The GSS tracked a slight, but not statistically significant, decline in the Catholic share of the population between 2006 (when GSS first conducted interviews in both English and Spanish) and 2012. But this decline was followed by a slight uptick in the Catholic share of the population in the 2014 GSS. The Catholic share of the population declined fairly steadily in aggregated Gallup polls between the late 1990s and 2010. It has inched upward since then, but it has not returned to late-1990s levels. Similarly, Washington Post-ABC News surveys found small declines in the Catholic share of the population between 2001 (24%) and 2010 (20%), before it ticked back up to 21% in 2011 and 2012, then to 22% in 2013 (when interviews were first conducted in both English and Spanish) and 23% in 2014.

The ARIS studies found that the Catholic share of the population held fairly steady between 1990 (26.2%) and 2008 (25.1%). By 2012, however, surveys conducted by SSRS using the same question and same basic methodology employed in the ARIS studies found 22.0% of adults identifying as Catholic, a decline of 3.1 percentage points since the 2008 ARIS.³⁰ This closely mirrors the trajectory for Catholics observed between the 2007 and 2014 Religious Landscape Studies. The findings of the 2014 Landscape Study also track closely with results from aggregated monthly polls conducted by the Pew Research Center that show a recent decline in the Catholic share of the population.

There are a number of factors that might help explain the differing estimates of the size of the Catholic population. Comparison of the GSS and the Landscape Study, for instance, shows that the 2014 GSS sample included a slightly higher share of Hispanics than the 2014 Religious Landscape Study (17% vs. 15%). It also had fewer interviews with young adults between the ages of 18 and 24 (9% in the GSS vs. 14% in the Landscape Study).³¹ This helps explain part of the difference between the 2014 Landscape findings and the 2014 GSS, since Hispanics identify as Catholic at a higher rate than the rest of the U.S. population, and younger Millennials identify as Catholic at a lower rate than do older adults.

Readers should also bear in mind that different methods and different questions can produce different results in surveys. The GSS consists primarily of in-person, face-to-face interviews, while the Landscape Study, other Pew Research surveys, Washington Post-ABC News polls, ARIS/SSRS surveys and recent Gallup polls are all conducted by telephone. And all of the surveys analyzed here ask different questions to measure religious affiliation. The GSS, for example, asks “What is your religious preference? Is it Protestant, Catholic, Jewish, some other religion, or no religion?” Gallup surveys have asked about religious identity in a variety of ways over the years, with its recent surveys asking “What is your religious preference – Protestant, Roman Catholic, Jewish, another religion, or no religion?” The Post-ABC trends are based on an open-ended religion question (“What, if anything, is your religion?”), as are the ARIS/SSRS data (“What is your religion, if any?”).

The 2014 Religious Landscape Study (and Pew Research monthly polls) asks a longer question with a more extensive list of options, including three separate chances for respondents to identify with no religion: “What is your present religion, if any? Are you Protestant, Roman Catholic, Mormon, Orthodox such as Greek or Russian Orthodox, Jewish, Muslim, Buddhist, Hindu, atheist, agnostic, something else, or nothing in particular?”³² By explicitly offering respondents the chance to identify as atheist, agnostic or “nothing in particular,” the Religious Landscape Study question may make it easier for marginally religious people who once thought of themselves as Catholics, Protestants or members of another religious group to identify as religious “nones.” This underscores the importance of taking methodology, question wording and other factors into account when comparing results from one survey to another.

Details on Data Sources

General Social Surveys were conducted once annually from 1972-1978; in 1980; in 1982; once annually from 1983-1991; in 1993; and once every two years beginning in 1994. Sample sizes for GSS surveys range from 1,372 to 4,510 and average about 2,000. For more information, see: Smith, Tom W, Peter Marsden, Michael Hout, and Jibum Kim. General Social Surveys, 1972-2014 [machine-readable data file] /Principal Investigator, Tom W. Smith; Co-Principal Investigator, Peter V. Marsden; Co-Principal Investigator, Michael Hout; Sponsored by National Science Foundation. – NORC ed. – Chicago: National Opinion Research Center [producer]; Storrs, CT: The Roper Center for Public Opinion Research, University of Connecticut [distributor], 2013.

The American Religious Identification Surveys (ARIS) were conducted in 1990 (n=113,713), 2001 (n=50,281) and 2008 (n=54,461). The principal investigators on the ARIS studies are Barry A. Kosmin and Ariela Keysar of Trinity College, Hartford, Conn. The ARIS results are compared with findings (provided in correspondence) from surveys conducted by Social Science Research Solutions (SSRS) in 2012 and early 2013 (n=61,412). SSRS is the research firm that conducted interviewing for the ARIS studies.

Trends from Washington Post-ABC News surveys were graciously provided to the Pew Research Center via correspondence. Data from Post-ABC polls are available for download from the Roper Center for Public Opinion Research.

Gallup data were accessed at http://www.gallup.com/poll/1690/religion.aspx.

Results from Pew Research Center monthly surveys reflect yearly aggregated data from polls conducted in 2009 (the first year in which most Pew Research Center surveys were conducted in both English and Spanish) through 2014. In total, this analysis draws on more than 50 separate polls and interviews with more than 110,000 respondents. See https://alpha.pewresearch.org/pewresearch-org/.