Americans are fickle consumers of religion, with about half changing religious affiliations at least once in their lives as they drift away from childhood traditions or stop believing in the teachings of their faiths, according to a national survey released Monday.
Such religious switching has swollen the ranks of the unaffiliated, according to researchers from the Pew Forum on Religion & Public Life.
Still, religion remains a strong force in American life, even among those raised in nonreligious homes.
"Many times, changing religions is a gradual process rather than a decision or event that takes place at a particular moment," Greg Smith, a forum research fellow, said Monday.
The survey, "Faith in Flux: Changes in Religious Affiliation in the U.S.," is a follow-up to a major study released last year by the Pew Forum. The 2008 analysis found that 44% of U.S. adults have switched religious affiliations or abandoned ties to a specific religion.
Monday's survey, based on follow-up interviews with 2,800 people, delved more deeply into the reasons behind the religious churn among Roman Catholics, Protestants and the unaffiliated. Jews, Muslims and other groups were not included because their numbers were not large enough to produce reliable results, the researchers said.
The survey found that most people who leave their childhood faith do so by the age of 24, and many change religions or denominations more than once.
The researchers found 16% of the adult population to be unaffiliated. Most said they had moved away from religious observance because they no longer believe in God or religious teachings. Many without religious belief also said they found religious people to be hypocritical, judgmental or insincere.
Even so, many of the unaffiliated said they were open to the possibility of one day finding a religion that suited them; about one-third said they had yet to find the right one. And, paradoxically, most who were raised unaffiliated said they now belonged to a religious group, either because they had felt spiritually unfulfilled or found religious services attractive, the survey showed.
Among other findings, the report found that 10% of American adults who were raised Catholic have left the faith, although their losses have been largely countered by significant immigration of Catholics from Latin America.
In most cases, former Catholics who are now unaffiliated said they were dissatisfied with the church's teachings on abortion, homosexuality, birth control or treatment of women.
More than two-thirds of those Catholics who switched to Protestantism, meanwhile, said that their spiritual needs were not being met and that they found another religion they preferred.
Only about one-quarter of former Catholics surveyed cited the clergy sexual abuse scandal as a factor in their departures.
"It doesn't appear this scandal was a major motivation for many people to leave, but it could have been a secondary reason," said John Green, a senior fellow with the Pew Forum and a political science professor at the University of Akron in Ohio.
Catholic Church officials said the survey underscored what they called the resilience of the Catholic faith. As evidence, they cited one finding in particular -- that 68% of those raised Catholics have remained in the faith.
"The report highlights the importance of Mass attendance among children and teenagers," said Archbishop Donald W. Wuerl of Washington, the incoming chairman of a committee overseeing church doctrine for the U.S. Conference of Catholic Bishops. "Adolescence is a critical time in religious development."
The survey also showed that 80% of those raised as Protestants have remained so. But more than a quarter of them have switched to a different Protestant tradition -- for example, changing from Presbyterian to Episcopalian.
Those who shifted said they had done so for a variety of reasons. Some told researchers they had drifted away or found a tradition they liked more.
Others said they had moved to a new community, married someone from a different religious background or were dissatisfied with the atmosphere at worship services, the report said.