to political crises and jokes and all kinds of stuff. (e.g. "I'm not exactly a Jew, but I am Jew-ish...")

The ethnic case is undeniable. Part of it is that so many modern Jews come from just a few places. I read that almost all Ashkenazi Jews may have come from just a handful of towns. Probably other groups of Jews petered out or, frankly, were killed.

Anyway, point is that Jewishness has an ethnic piece and even Judaism as a religion is very broad. There are secular Jews. Agnosticism, even if it is not Judaism exactly, is within the spectrum of what one could consider Jewish belief along with the branches of Judaism varying degrees of orthodoxy/literalism.