In terms of major traditions, more than one of four Americans (28%) have changed their affiliation from that which they were born in. If you consider those who change within a tradition (so, from one Protestant group to another, or going from Orthodox to REform Judaism, etc.), you end up with a number like 44% of Americans changing their religious affiliation from that which they were born in.
Clearly Americans are on the move religiously. But who is winning and losing out? Evidently, the largest religious group (or the group gaining the greatest percentage increase in adherents) is "unaffiliated." That's right. This group contains former Catholics, Jews, Hindus, Protestants. So the tradition that is gaining the most adherents seems to be that amorphous tradition of "no tradition."
Non-Denominational Protestants show huge growth as well: tripling in size due to religious migration.
Many groups have shown loss, but the biggest net loss of all religious groups in the U.S. is among Catholics. According to the survey, 31.4% of adults say they were raised as Catholics, but only 23.9% of them identify as Catholic today, showing a net loss of 7.5%. Note that this is a net loss. 2.6% of the U.S. population has converted to Catholicism, which means that 10.1% has converted from the Catholic Church. Catholics in the U.S. , however, have been able to maintain roughly the same numbers in gross terms due to immigration from primarily Catholic countries, especially from Central and South America. And so the changing face of one tradition is much more dynamic than a simple net loss/gain indicates.
After Catholics, the next greatest net loss is among Baptists, who have lost 3.7%.
Many groups (although perhaps not showing much net gain or loss) have a very high incoming /outgoing dynamic. so, about 2/3 of Jehovah's Witnesses were born in another tradition. They simply lose a lot of their membership as well, showing a low net gain/loss. LIkewise with teh non-affiliated (about 2/3 were born affiliated with something). And among Buddhists in the U.S. , 3/4 were born as something else.
On the other end of things, in indications of stability, despite losing so many adherents, 89% of Catholics were raised Catholic. Also 90% of Hindus were raised Hindus, and 85% of Jews were raised Jewish.
Interestingly, evangelicals have only 51% of their membership being raised evangelical. They draw a very large portio of their membership from other Protestant denominations (31%), while the balance comes from other traditions. This is actually roughly similar to the configuration of mainline protestant churches as well. Because of this Protestant trading, although they change their religious traditions and sometimes very drastically (the different between the SBC and the UCC are HUGE), 80% of those raised as some sort of Protestant, stay within some sort of Protestant tradition.
While nearly all people who join a Protestant group came from another Protestant group, this survey finds that 1 out of 10 protestants were raised CAtholic. Where are those who were former Protestants going? Mostly to "unaffiliated." In fact, former Protestants make up nearly half of the unaffiliated group, and former Catholics about a fourth.
What I find interesting is the demographics of conversion. Amogn men, women, all ages and all classes and all levels of education, the percentage of conversion is in the 40s, except amogn Latinos (35%) and Asians (37%) on one hand, and those who claim mixed racial ancestry (54%) on teh other. The differences are rather on what type of conversion one undergoes. The younger one is, it seems, the more one is willing to go further outside of one's tradition (so from Protestant Christianity to Buddhism, etc.), while older converts change to more comparable trditions (like from one protestant denomination to another).
Another issue is religiously mixed marriages. 27% of married adults married someone from another religious tradition (and if you include Protestants who married a different type of Protestant, 37%). This also tends to be more and more common among younger married couples. On the other hand, Hindus (90%), Mormons (83%), Catholics (78%), and Jews (69%) are the most likely to stay within their own tradition. 81% of Protestants are married to other Protestants, but only 63% of those are within their same PRotestant group. Unaffiliated are more likely to marry someone who is affiliated with something than with another unaffiliated person.