BA2, thx for the PEW study link. Interesting, given how the decline of religion in almost all areas of American subculture, liberal/conservative, Christian/Jewish, Protestant/Catholic has been going on for decades now. If it has indeed been leveling off, that's a significant change.
The one place it has been increasing is in the extreme right wing of evangelical Protestants, Trump supporters and all.
RG, that's an important observation re: Islam. I realize you're speaking of those native lands. I wonder if that's true among Moslem immigrants to the USA, especially the first-generation born-ins whose parents immigrated. Do they have the same fervor for Islam that their parents have, or are they becoming secularized like the young native-born American Jews, Protestants, and Catholics are? I remember having a young doctor not long back whose parents immigrated from the Middle East. He had a typical Arab last name, El- or Ab- something that was definitely Arabic. I asked him once about something about Arabic. He looked at me blankly and said, "I don't know about that stuff" with a degree of disdain. He wound up marrying an attractive blonde American woman. Their kids surely won't be raised Moslems!