When looking at changes from one major religious tradition to another including no religion at all more than one-in-four adults (28%) have changed their religious affiliation from that in which they were raised. Among those changing their affiliation, the largest number now say they are not affiliated with any particular religious group or tradition. Another group that shows a net gain as a result of affiliation changes is nondenominational Protestants, whose share of the population has more than tripled as a result of such shifts. The denomination that has experienced the greatest net loss by far is the Catholic Church.
Source: Pew Research Center