The United States, founded by dissident Protestants seeking religious freedom, is on the verge of becoming a nation in which Protestants are a minority.
A growing fraction of Americans identify themselves as unaffiliated with any religious tradition, and a small but increasingly significant number say they are Muslim, Hindu, Buddhist, or Orthodox Christian. And a flood of overwhelmingly Catholic immigrants, mostly from Latin America, is helping to offset a high dropout rate among US-born Catholics
These are among the key findings of a groundbreaking study of the American religious landscape released yesterday by the Pew Forum on Religion and Public Life. The study, which is the most comprehensive such examination of the country in at least a half century, finds that the United States is in the midst of a period of unprecedented religious fluidity, in which 44 percent of American adults have left the denomination of their childhood for another denomination, another faith, or no faith at all.
"Americans are not only changing jobs, changing locations, changing spouses, but they're also changing religions on a regular basis," said Luis E. Lugo, director of the Pew Forum. "We have nearly half the American public telling us they're something different today than they were as a child, and that's a staggering number. It's such a dynamic religious marketplace and very competitive."
The study is based on a survey of 35,000 Americans age 18 and over, a very large number for survey research, and the size of the pool allowed the researchers to get more detail about minority religious groups than is usually available from smaller studies. The study is also important because the quantification of religious affiliation in the United States is often difficult and contested; the US Census does not include questions about religion, and many studies rely on counts submitted by denominations, whose self-reporting is often unreliable.
Protestantism in America has been declining at least since the 1980s, the researchers said, when about two-thirds of Americans identified themselves as Protestant. Scholars have debated the causes of the decline, but said it might be due in part to low birth rates among mainline Protestants and difficulties among mainline Protestant churches in retaining the children of their members.
"The continuing decline in the size of Protestantism is very important for American culture and American politics," said John C. Green, a professor of politics at the University of Akron and a fellow at the Pew Forum. The traditions of civility, tolerance, and individualism are values that arose from Protestantism, Green said. "So much of our values and institutions in American public life came out of mainline Protestantism."
The new study is filled with findings about a remarkably diverse nation, with a population that is shaped by affiliation with a vast and shifting array of religious groups and sects. Every religious family - Christians, Jews, Muslims, and Buddhists - is represented by a number of subgroups. Scholars believe, for example, that the Muslim population of the United States - which is made up of African-Americans, whites, and immigrants from both south Asia and the Arab world - is more diverse than anywhere else.
"Every indication is that adherents of these other world religions - such as Islam, Buddhism, Hinduism, etc. - will continue to grow as a percentage of the US population," Lugo said. "It is now at 5 percent, which is not insignificant. When the census bureau took its own numbers back in the '50s, these groups were virtually a rounding error. So, clearly they are growing, and we know that you don't need a high percentage of folks who are new or different, as perceived by most folks in the society, to generate a lot of conversation, not least in politics."
The nation is still predominantly Christian - 78 percent of adults say they are Christian - but nearly 5 percent identify themselves as members of other faiths, and 16 percent say they are unaffiliated.
The largest single faith tradition in the country is evangelical Protestantism, with about 26 percent of the adult population; followed by Catholicism, at 24 percent; mainline Protestantism, at 18 percent; the unaffiliated, at 16 percent; and historically black Protestant churches, at 7 percent.
Evangelical Protestantism appears to be growing, but its growth is being dwarfed by a decline in mainline Protestantism, and the result is that just 51 percent of Americans are now Protestant, the brand of Christianity that has dominated this nation's history, generating all but one of its presidents and dominating its town squares.
"There is no question that the demographic balance in American Protestantism has shifted in the last several decades decidedly in the direction of evangelical Protestant churches," Lugo said.
The average age of mainline Protestants, as well as Jews, is also higher than for other faith groups.
The willingness of Americans to change their religion is a relatively new phenomenon, after generations in which one's faith was largely determined by the faith of one's parents.
And the survey found that about 37 percent of adults are married to someone with a different religious or denominational affiliation; many conversions do not appear to be driven by marriage, the researchers said.
"The study confirms that religion in America is achieved, rather than ascribed - it's something we choose - and, in that sense, it is so different from what religion has been like for the previous 2,000 years of history," said Alan Wolfe, director of the Boisi Center for Religion and American Public Life at Boston College, who reviewed the study.
The study determined religious affiliation simply by asking respondents their religion and denomination. Later this year, the Pew Forum plans to release studies exploring the beliefs and practices and the social and political views of members of different religious traditions.
Among the study's more unusual findings: Jehovah's Witnesses have the worst record of any faith group at retaining their members. Hindus and Mormons are the least likely to be married to someone of another faith, and the least likely to be single. Mormons and Muslims have the biggest families. Three-quarters of American Buddhists are converts. Jews are the highest-income group in America, but Hindus are now the best educated: Nearly half of all adult Hindus have some post-graduate education.
Catholicism, the biggest single denomination in the country and the dominant faith group in the Northeast, is losing members nationwide faster than any other major grouping.
One in three people raised Catholic is now a former Catholic, the study finds, and, as a result, 1 in 10 Americans is now a former Catholic.
Yet, the overall Catholic population in the country remains fairly stable, because most immigrants today are Catholic.
"If you remove immigrants, then Catholicism is in free fall, the way Episcopalianism and other mainline religions were 20 or 30 years ago," Wolfe said.
The study finds that among former Catholics, a little less than half are now Protestant and about the same number are unaffiliated.
Latinos make up only one in eight Catholics over age 70, but half of those between ages 18 and 29, strongly suggesting that the makeup of the Catholic Church, which is now one-third Latino, will become increasingly Latino over time.
Locally, the Archdiocese of Boston already offers Mass in Spanish at about 40 parishes, and counts several hundred thousand Hispanics among its parishioners. Priests who work with Hispanics in the Boston area say the change is visible throughout the church.
"The Hispanicization brings a tremendous dynamic into the church, with a love of Mary and a wonderful sense of celebration of life and celebration of faith," said the Rev. James J. Ronan of St. Mary-St. Catherine of Siena Parish in Charlestown, which just consolidated two congregations, one predominantly white and the others with a substantial Hispanic minority.
But Ronan said the integration of the church also poses challenges, adding that "people are also struggling to work this out, because it's not easy to do."
Ronan expressed skepticism about the permanence of findings that show people leaving Catholicism, saying his experience is that many come back.
"I would be reluctant to take at face value a response that's a Catholic saying, 'I'm no longer a Catholic,' because things change, people find themselves looking for bigger answers, and they revisit it and they come back," he said.
The study finds that Massachusetts is more Catholic and more Jewish than the nation at large and that the state has fewer evangelicals and fewer African-American Protestants.
In general, the study confirms, the Northeast remains the most Catholic region, the South the most evangelical, and the West the most unaffiliated.
Paulson can be reached at mpaulson@globe.com. The study is available at pewforum.org.
