FACTBOX: Key findings of religion survey

(Reuters) - Twenty-eight percent of U.S. adults have left the faith in which they were reared, according to a survey by the Pew Forum on Religion & Public Life issued Monday.

Following are some other findings by the survey of religion in the United States.

* If change in affiliation from one type of Protestantism is included, 44 percent of adults have switched religious affiliation, moved from being unaffiliated with any religion to being affiliated with a particular faith, or dropped any connection to a specific religious tradition entirely.

* Among people aged 18 to 29, 25 percent said they are not affiliated with a particular religion.

* Fifty-one percent of Americans say they belong to Protestant denominations.

* While 31 percent of Americans were reared in the Catholic faith, 24 percent now characterize themselves as Catholic.

* Among the foreign-born adult population, 46 percent are Catholic and 24 percent are Protestant. Among the U.S.-born population, 55 percent are Protestant and 21 percent are Catholic.

* Mormons and Jews each comprise 1.7 percent of the overall adult population.

* Muslims, approximately two-thirds of whom are immigrants, account for about 0.6 percent of the adult U.S. population.

* Nearly 20 percent of men and 13 percent of women said they have no formal religious affiliation.

(Writing by Paul Grant, Washington Editorial Reference Unit; editing by Michael Conlon and Vicki Allen)