A new study looks for answers, and Michael Paulson, over at Articles of Faith, has a good wrapup:

Americans are changing their religious affiliations at unprecedented rates, but Catholics are much more likely to cite concerns about their religion as a reason for leaving than are Protestants, who more often cite changing life circumstances.

The churn within American religion — about half of American adults have changed their faith affiliation at some point — was one of the key findings of a major study released last year by the Pew Forum on Religion & Public Life; today, the Pew Forum is releasing a new study that attempts to explore the reasons why Americans change denominations or religions, or, increasingly, drop out of institutional religion altogether.

Among the most striking findings are that most people who change their religious affiliation leave the denomination in which they were raised by age 24, and many change religious affiliation more than once. And the study found that the growing population of unaffiliated Americans are more disenchanted with institutionalized religion than with the idea of God.

But the differences between Catholics and Protestants are also significant, suggesting that Catholics who become alienated from their church often leave, whereas Protestants have the option of simply switching denominations.

“Protestants show a lot of interdenominational mobility, in part because there are a lot of Protestant groups,” said John C. Green, a political science professor at the University of Akron. “Among Catholics, there is much less scope for mobility within the denomination, and a larger number ended up leaving.”

The study finds that about half of former Catholics cite religious and moral beliefs as the reason they left the Catholic church. About four in 10 former Protestants who became unaffiliated offer a similar explanation, but among Protestants who simply switch denominations, the main reasons are concerns about particular religious institutions, and life cycle changes such as marriage.

Pew last year released the eyepopping estimate that one in ten Americans is now a former Catholic — about half of the former Catholics are now Protestants, and about half are now unaffiliated. But the new study suggests that the sexual abuse crisis played at most a minor role in the decision of Catholics to leave — only two percent of former Catholics who are now unaffiliated volunteered the abuse scandal as the main reason they are no longer Catholic; when prompted by an interviewer, 27 percent said concern about the abuse scandal was a factor in their departure. Former Catholics who are now unaffiliated often said they left because of disagreements with the Catholic church over homosexuality, abortion, birth control, or gender; former Catholics who are now evangelical often say they stopped believing Catholic teachings and are concerned with the Catholic church’s teachings about the Bible, while former Catholics who are now mainline Protestants most often say they changed because of marrying a non-Catholic or because they didn’t like their priest.

“The sex abuse crisis is nowhere near being among the most important factors explaining why people have left the church,” said Mark M. Gray, director of the Catholic Poll at Georgetown’s Center for Applied Research in the Apostolate. Gray noted that many Catholics who became Protestants cited not one of the culture war issues, but teachings about the Bible.

“Clearly, there’s a need to try to connect with youth, because a big portion of the people you’re losing are teenagers and in their early 20s, and there’s a need to reach out to them in terms of spiritual needs not being met,” Gray said.

There’s much more, with lots of links, at the Globe link.