On the heels of a study of the U.S. "religious landscape" released last year that showed a quarter of Americans had changed faiths, a follow-up survey has found an even greater rate of "Faith in Flux," as the latest report is called.

When the number of people who now practice a different faith than that of their childhood is added to those who have moved around among religions or denominations and come back to where they started, nearly half of Americans have changed religions at some point, said the report by the Pew Forum on Religion & Public Life released April 27.

Among people who have changed religions, those who left the Catholic Church were more likely than those who left Protestant denominations to have done so because they no longer believed the teachings of the church, the study found.

It also made connections between how actively involved people were in their churches as children and teens and how likely they were to leave the faith in which they were raised.

Across the board, the vast majority of people who changed churches, who stopped being affiliated with any faith or who transitioned from being "unaffiliated" with a religion to belonging to a church did so before the age of 24, the survey found.

The reasons cited most often by those who have left the Catholic Church were that their spiritual needs were not being met, that they "just gradually drifted away" or they "found a religion they liked more."

Greg Smith, research fellow for the Pew Forum, told Catholic News Service that among the more striking conclusions of "Faith in Flux" were the reasons people gave for leaving the Catholic Church, depending upon whether they joined evangelical or mainline Protestant denominations.

Fifty-three percent of Catholics who became evangelicals said they left because of religious and moral beliefs, principally teachings on the Bible.

By comparison, 28 percent of Catholics who joined mainline Protestant denominations left because of differing beliefs. The main reasons for leaving cited by 40 percent of that group fell under the category of "religious institutions, practices and people," including dissatisfaction with particular churches or clergy or objections to rules. The single largest factor cited by Catholics who joined mainline Protestant churches, however, was "family reasons," such as marrying someone of another faith, mentioned by 31 percent.

Nearly half the people who left the Catholic Church, 48 percent, did so before age 18, the survey found. One-third of Protestants who changed faiths left before 18, they said.

Among both Catholics and Protestants, high percentages of those who have stayed in their churches were active in religious activities in their youth.

The Pew study said 46 percent of people who have remained Catholic described their faith as strong when they were children.

Those who regularly attended Mass as children and teens were more likely to have remained Catholic. Similarly, those who attended their Protestant churches regularly as teens also were more likely to stay in the faith of their childhood.

But participation in religious education as a child, or in youth groups as teens, appears to have had little statistical difference in whether childhood Catholics are still Catholic.

The study found that 71 percent of people who are still Catholic attended religious education as children, compared to 68 percent of Catholics who became Protestants and 68 percent of those who now belong to no organized religion. Thirty-two percent of current Catholics participated in Catholic youth groups, compared to 39 percent of Catholics who became Protestants and 32 percent of former Catholics who are unaffiliated.

Eighty-six percent of people who are still Catholic said they attended church weekly as children, as did 74 percent of those no longer affiliated with a religion and 79 percent of Catholics who became Protestants. Sixty-nine percent of current Catholics attended church regularly as teens, compared with 60 percent of converts to Protestant religions and 44 percent of people who are unaffiliated with churches. Sixty-three percent of those still in the Protestant church of their childhood attended services weekly as teens, the study said.

In a statement issued by the U.S. Conference of Catholic Bishops, Washington Archbishop Donald W. Wuerl said the report highlights that "adolescence is a critical time in religious development," and that "what happens in the teen years has a long-lasting effect."

Archbishop Wuerl, past chairman of the bishops' Committee on Catechesis and next chairman of their Committee on Doctrine, said the data shows that "we have to help young people and their parents appreciate the importance of going to weekly Mass so teenagers know Jesus is there for them now and always."

One-quarter of lifelong Catholics attended Catholic high schools, the survey said. Of Catholics who became Protestants, 16 percent went to Catholic high school, as did 20 percent of former Catholics who no longer are involved with a religious group.

For this survey, Pew researchers re-interviewed more than 2,800 people from across the country who participated in the comprehensive "U.S. Religious Landscape Survey." Results were categorized by whether people said they were "nonconverts," either by remaining in the faith of their childhood or continuing to be unaffiliated with any religion, and by whether people had switched from Catholicism or a non-Catholic faith, had changed churches within Protestantism, or had joined or left a non-Catholic faith after being unaffiliated with any religion.

Smith explained to CNS that the survey was unable to provide data on people who became Catholics because of the small number who were interviewed. Although those who switched to Catholicism make up 2.6 percent of the U.S. population, Smith said, that translated to just 69 interviews for this survey, too few from which to draw statistically meaningful conclusions.

Of those 69, Smith said about half had come from other Christian churches and half previously had no religious affiliation. That breakdown made it even harder to use the data as representative of all those who became Catholic.

He said he also was aware that it's significantly more complicated for an adult to officially become Catholic than it is for people to join other faiths. New Catholics typically participate in a months-long education and discernment process through the Rite of Christian Initiation of Adults. People join many other religions or Christian denominations by little more than participating and deciding that it is now their church.

"Faith in Flux" noted that those who have left the Catholic Church outnumber those who have joined it by nearly 4-to-1. "Overall, 1 in 10 American adults (10.1 percent) have left the Catholic Church after having been raised Catholic, while only 2.6 percent of adults have become Catholic after having been raised something other than Catholic," the survey said.

The statistical margin of error for the survey ranges from plus or minus 5 percentage points to plus or minus 10 percentage points, depending upon the segment being analyzed.

---CNS