The overall apostasy rate for Americans (defined as leaving their childhood religion) is over 25%, or to put it backwards, the overall retention rate is 75%.
Protestants remain solid, although their percentage of all Americans is slowly dropping over the decades. 80% of Protestants children are retained as Protestant adults (although not necessarily of the same denomination), and 81% marry another Protestant (63% marry within their specific Protestant denomination).
Baptists, who account for one-third of all Protestants and close to one-fifth of the total U.S. adult population, have a 60% denominational retention rate (staying Baptist), which is the highest among all Protestant groups. 83% of childhood Baptists remain some flavor of Protestant, also the highest percentage. Methodists had a retention (as Protestant) rate of 79%, Lutherans 78%, Presbyterian 76%, and Congregationalists 72%. On the other end of the Protestant spectrum, only 68% of childhood Episcopalians remained Protestant, with a full 20% of them becoming unaffiliated.
Catholics have a 32% apostasy rate (i.e. 68% retention), as 31% of all Americans were raised Catholic, but only 24% remain Catholic. High immigration levels of Hispanics have kept them at a stable level of the overall population. Surprisingly, half of all Catholics under 30 are Hispanic, and almost half of all Catholics under 40. 78% of Catholics marry another Catholic.
Just under 2% of all Americans identify as Mormon, around 4 million total. Calculating only conversions versus apostates, Mormons are losing numbers, with an apostasy rate of 30% (i.e. 70% retention).
The cultish nature of Mormonism is highlighted by the fact that they had the highest rate of in-group marriage, with over 84% of Mormons married a fellow Mormon. Mormons are the most likely white Americans to be married, at 71%. Mormons also have the most kids, with more than 20% of Mormons reporting three or more children living at home.
Jews make up 1.7% of Americans, about 3.8 million total, and over 70% of them are Reform or Conservative. Jews are the wealthiest religious group, with over 50% of the reporting an income over $100,000 per year. 69% of Jews marry another Jew. The Jewish retention rate is 76%.
For some reason, the Pew survey did not report the retention/apostasy rate of Muslims. However, the incredible-shrinking nature of American Islam is highlighted by the fact that there were actually more Buddhists than Muslims in this latest survey (0.7% versus 0.6%) and almost 3 times as many Jews. There are as many Eastern Orthodox Christians (Russian and Greek primarily) as there are Muslims.
Hindus were highly likely to marry another Hindu (90%), but that has more to do with their status as a racially-distinct new-immigrant community (88% of Hindus are Asian and 90% were raised Hindu). The ethnic-identity element of Hinduism is also highlighted in their apostasy rate, a very low 16% (i.e. 84% retention rate). Interestingly, Hindus are also the most likely group to be married (78%).
The weak future of Buddhism in America is also highlighted by the Pew survey. Buddhists are the least likely to marry another Buddhist (only 45%), and the most likely to switch away from their childhood Buddhism (50% apostasy rate). Interestingly, only 22% leave Buddhism for another religion, while 28% convert to unaffiliated. Unlike Hinduism, 53% of all American Buddhists are white. Buddhism appears to be an experimental religion for most, especially for the previously unaffiliated, with 30% having joined from another religion and 12% converting from the previously unaffiliated (the highest such percentage in America).
Jehovah’s Witnesses are extremely demanding of their members, in terms of moral/behavioral requirements and prohibitions, and it shows in the apostasy rate: 63% of children raised as JWs leave the faith (33% of them convert to no religion at all/unaffiliated, only 30% going to another religion), which is the highest apostasy rate in America. Just under 1% of Americans are JWs.
The religiously unaffiliated, call them the religiously apathetic, number 12%. Only 7% report being raised unaffiliated. Over half of those raised unaffiliated eventually joined a religion.
Agnostics and atheists account for only 4% of American adults today.
Summary chart (retention rate in descending order)
Jehovah’s Witnesses 37%
[Pew Forum's U.S. Religious Landscape Survey, which draws primarily on a new nationwide survey conducted from May 8 to Aug. 13, 2007, among a representative sample of more than 35,000 adults in the U.S., with additional over-samples of Eastern Orthodox Christians, Buddhists and Hindus.]
See source reports at: