Sometimes one's culture is most clearly seen from the vantage point of another friendly country. The Daily Mail (U.K.) reports recent analysis of NORC/Associated Press survey data concerning religious affiliation in the U.S. Hat tip to Drudge Report for the link.
The chart of U.S. religiosity by category since 1972 (scroll down) is excellent at giving a picture of what has occurred over time. Over the last three decades there has been little change in the percentages represented by Catholics, Jews, Black Protestants, Evangelicals, and Others. What has declined dramatically is "Mainline Protestants" and what has increased nearly as much is those with no religious affiliation, called "Nones."
Roughly 22-23% each are Catholics, Evangelicals, and Nones - the three largest groups. The other four groups are each in the 2-10% range.
There is a temptation to view what happened as a straight-line exit of Mainline Protestants becoming Nones. I believe the changes are more complex than a simple headcount suggests. It is likely half or more of our recent, often illegal, immigrants from Central and South America are Catholic, and have replaced millions of domestic Catholics who've lapsed.
It is also true, though unmentioned in the DM article, that "Jew" is both a faith and an ethnicity. The unchanging number of self-reporting Jews likely conflates the two definitions. One can stop practicing a faith, changing one's ethnicity may be effectively impossible in the short-to-medium run.
