Why so many Americans switch religions

America is a country on the move in innumerable ways, and religion is no exception. Half of Americans have changed their religious denomination at least once in their lives – many several times – and 28 percent have switched faiths altogether (for example, from Christianity to Judaism). Amid this fluidity, the number of "unaffiliated" adults has grown to 16 percent of the population.

What is behind such extraordinary "churn" in US religious life? As a follow-up to its pathbreaking 2007 survey of the American religious landscape, the Pew Forum on Religion & Public Life released a new survey Monday – "Faith in Flux" – that explores in depth the patterns and reasons for such remarkable change.

Most people who switch their allegiance during their lifetime, the survey finds, leave their childhood faith while they are still young, before the age of 24. Yet the opportunities for attracting them to another religion appear to continue for some time.

The reasons for leaving differ according to the origin and destination of the convert. Roman Catholics, for instance, tend to leave because they don't accept certain church teachings. Those Protestants who switch denominations do so more often in response to life changes such as relocation or marriage, or because of dislikes about institutions or practices.

While 56 percent of US adults remain in their childhood faith, 16 percent left, joined another house of worship at least once, and then returned to their original fold.

Of those raised Protestant, 80 percent remain so, with 52 percent still in their childhood denomination. Twenty-eight percent have moved to another Protestant following, 13 percent are now unaffiliated, 3 percent have become Catholic, and 4 percent joined other faiths.

Of those raised Catholic, 68 percent remain in the faith, 15 percent are now Protestant, 14 percent unaffiliated, and 3 percent in other faiths.

As several polls have shown, the "unaffiliated" is the fastest growing group in the past two decades. Yet the Pew survey shows this group to be very diverse, and often serving as a way station for many still seeking a religion.

While about 40 percent in this group say they don't believe in God, another 40 percent say religion is somewhat important in their lives, and roughly one-third say they just haven't found the right religion yet.

"We do not see a kind of principled, fundamental rejection of a religious worldview," says Greg Smith, a Pew researcher.

At the same time, 55 percent say they became unaffiliated because they found religious people hypocritical and judgmental. Many view religion as too focused on rules and not enough on spirituality.

For Candace Talmadge, a writer from Texas who grew up in a mixed-faith family, an unhappy experience in Sunday school set her on a path away from regular church attendance.

"When a little girl has a Jewish grandparent and the teacher says Jews are going to hell, it's not conducive to a sense of belonging," Ms. Talmadge explains. She stopped going to church as soon as she could and eventually found her own spiritual path.

"I do believe in God, and our spirituality is inherent in who we are," she says. "Religion is man-made dogma.... Spirituality is God-made. Spiritual practice for me is very individualized."

The survey also finds that some 7 percent of Americans were raised without a religious affiliation, but most of them have become religious: Forty percent are Protestant, 6 percent Catholic, and 9 percent in another faith. Among the reasons they give for joining are the enjoyment of worship services and their sense of being spiritually unfulfilled while unaffiliated. Half said they felt called by God to join a religious community.

In the shifting religious landscape, Catholicism has lost the most members: Ten percent of Americans are former Catholics, and those who have left the church outnumber those who have joined by 4 to 1, the survey finds. (Immigration has enabled the church to maintain its 24 percent share of the US population.)

When asked to explain in their own words the main reason for leaving the Catholic Church, about half cite a disagreement with the church's religious or moral beliefs. For those now unaffiliated, about half were unhappy about birth control, 56 percent about teachings on abortion and homosexuality, and 40 percent about the treatment of women.

Mandy Burrell Booth, who works for a nonprofit group in Chicago, grew up in Catholic schools but began questioning what she was taught during college.

"I definitely believe in God, but I'm still sorting out who Jesus was," she says. Along with church teaching on birth control methods, "the politics and direction of the church didn't feel like I fit," she says.

After trying different churches, she and her husband are now part of a Unitarian Universalist congregation called Micah's Porch, which allows for asking lots of questions. "It's very creative, multimedia, and humorous, and much more about the here and now than many Christian services," she says.

Protestantism appears on the verge of losing its majority status in the United States (now at 51 percent), partly because of immigration but also because of the 13 percent who have joined the unaffiliated. Fifteen percent of Americans, however, have shifted from one Protestant denomination to another.

"There's a lot of vitality there, with people moving around and finding more congenial places," says John Green, a senior fellow at Pew Forum.

Most who have changed Protestant denominations say that they found one they liked more or that their spiritual needs weren't being met in their childhood church. About 40 percent were not satisfied with the atmosphere at worship services.

Neil Gussman became a Christian while in the US Air Force and has changed churches several times. At first he attended an independent church, but he became dissatisfied with the free form of prayers. "They were often both ungrammatical and tended to bad theology," he writes in an e-mail from Kuwait, on his way to deployment in Iraq.

Now his family attends a Presbyterian church, which is confessional and recites the creeds as part of services. "I know the prayers have been prayed by other believers for hundreds of years, that I am part of the whole Church," he adds.

For all those switching allegiances, whether Catholic, Protestant, or unaffiliated, the reason most often given for joining a new church is the appeal of the worship services.

"Faith in Flux" involved interviews with 2,800 adults who were also part of the 2007 Pew survey. Sample limitations prevented the inclusion of smaller groups (such as converts to Catholicism).

[Editor's note: The original version has been updated for clarity.]