WASHINGTON  More than a quarter of adult Americans have left the faith of their childhood to join another religion or no religion, according to a new survey of religious affiliation by the Pew Forum on Religion and Public Life.

The report, titled “U.S. Religious Landscape Survey,” depicts a highly fluid and diverse national religious life. If shifts among Protestant denominations are included, then it appears that 44 percent of Americans have switched religious affiliations.

For at least a generation, scholars have noted that more Americans are moving among faiths, as denominational loyalty erodes. But the survey, based on interviews with more than 35,000 Americans, offers one of the clearest views yet of that trend, scholars said. The United States Census does not track religious affiliation.

The report shows, for example, that every religion is losing and gaining members, but that the Roman Catholic Church “has experienced the greatest net losses as a result of affiliation changes.” The survey also indicates that the group that had the greatest net gain was the unaffiliated. More than 16 percent of American adults say they are not part of any organized faith, which makes the unaffiliated the country’s fourth largest “religious group.”