CHICAGO (Reuters) - When it comes to religion, more and more U.S. adults either have none or do not identify with a particular church, although the country remains highly religious, a survey said on Monday.

A parishioner at the 7,000-seat Willow Creek Community church in South Barrington, Illinois, in a 2005 photo. When it comes to religion, more and more U.S. adults either have none or do not identify with a particular church, although the country remains highly religious, a survey said on Monday. REUTERS/John Gress

The report from the Pew Forum on Religion and Public Life found a constantly shifting landscape of religious loyalties, with the Roman Catholic Church losing more adherents than any other single U.S. religious group.

One in 10 Americans now describes himself as a former Catholic, it found, although that church’s membership is constantly being replenished by immigrants, particularly Latinos.

Despite predictions that the United States would follow Europe’s path toward secularization, the U.S. population “remains highly religious in its beliefs and practices,” the survey concluded.

But John Green, a senior researcher with the Pew Forum, told reporters American religion appears headed for more diversity, with the likelihood the country will be “less Protestant and less Christian” in the future than it is now.

The survey, based on interviews with more than 36,000 U.S. adults, found 78.4 percent of the population identify themselves as Christian. Of U.S. adults in general, it said 51.3 percent were Protestant, 23.9 percent Catholic, 1.7 percent Mormon, 0.7 percent Jehovah’s Witness and less than 0.3 percent each Greek or Russian Orthodox.

“The biggest gains due to changes in religious affiliation have been among those who say they are not affiliated with any particular religious group or tradition,” the survey found.

“Overall 7.3 percent of the adult population says they were unaffiliated with any particular religion as a child. Today, however, 16.1 percent of adults say they are unaffiliated ... sizable numbers of those raised in all religions -- from Catholicism to Protestantism to Judaism -- are currently unaffiliated with any particular religion,” it added.

The survey did not seek to try to find why people abandon churches or join new ones. Greg Smith, a researcher at the forum, said it may be that younger generations are not reconnecting with religion as they age as previous generations did, a trend that if continued could have a profound impact on American religion.

IMMIGRANTS REPLENISH CATHOLIC RANKS

Evangelicals constitute the largest Protestant segment at 26.3 percent of the adult population, while 18.1 percent of adults belong to mainstream faiths such as Methodists or Presbyterians and 6.9 percent to historically black churches.

Jews were 1.7 percent of the population, including Reform at 0.7 percent, Conservative 0.5 percent and Orthodox 0.3 percent. Buddhists were estimated at 0.7 percent, Muslims at 0.6, Hindus at 0.4, other world religions 0.3, Unitarians and other liberal faiths 0.7, New Age 0.4 and native American faiths 0.3.

Even though this and other surveys have found the U.S. Catholic population fairly stable over the years, that masks the fact that “in total the Catholic Church has lost more adherents than any other single religious group in the United States,” the report said. Immigrants keep replenishing their ranks, it said.

There were about 225 million U.S. adults when the surveys were conducted in 2007. The survey said it had an error margin of plus or minus 0.6 percent.