On the Pew U.S. Religious Landscape Survey, 3
The Roman Catholic Church has been the largest denomination in the United States for five generations. Catholics make up about a quarter of the population. Yet the Catholic Church shows huge losses over a lifetime in the new Pew survey. Asking adults what religion they are now, and what they claimed as a child, the RCs show a 24% loss. Yet they remain nearly a quarter of the population. How is that possible?
Part of the answer is conversion. While 7.5% of the population reports that they once were Catholics but now are not, another 2.9% of the population made the shift the other way, making up almost 40% of the loss.
The other part of the answer is immigration. Almost half of all immigrants are Catholic. Immigrants make up nearly a quarter of the Catholic membership in this country - double the percentage of Americans who are foreign-born.
The Pew survey does not tell us when the exiting Catholics departed. It seems likely to me that there was a spike of departures in the wake of the recent priestly pedophilia scandals. If so, then the rate of departures is likely to slow down soon.
Still, for a group with such massive losses, the Roman Catholic Church is surprisingly and steadily robust in the United States.