Religion

Big enough to be included by size or importance.

So 7-8 days each, with Islam being up with what the Yazidi believe, is about right.

Because obviously it's as important to know what Manichaeans believe because we interact with them and they're important for understanding American/Western culture and reading decent literature as, say, Taoism and Sikhism.

My atheist Russian lit professor (8 wives, bipolar, who liked to say "fuck whatever you think god is" and meant it sincerely) always said before he went over the syllabus for the first class incoming grad students would have to take was that the first thing we should read in our first semester of grad school was at the very least the New Testament. In Russian. At least once in Russian and once in Church Slavic. Because if we didn't, we'd be lost for Russian literature written from 1085 up through 1988 (when I heard him say this on my first day in a grad literature class). Even Soviet writers made bible references because it was part of how people spoke.

When asked, because Marx-Lenin was such a big deal, if we should read those works, too, his response was that nobody hardly read them, read a dozen speeches and you'll see the quotes that are used. But to be careful, because it wasn't what the words meant in any compositional way but how they were interpreted and used that mattered, and while the former was fairly unchanging they were "living documents" and meant damned well whatever the rulers at the time meant them to mean.

In other words, some things matter more than others in a practical sort of way, whatever our a priori definition of fairness, with all due regard to resisting and showing how virtuous we are. Xianity (Western, not Eastern), Islam (Sunni, less other kinds), perhaps Hindusim or Buddhism. After that, what's left is trying not to offend somebody with a deeply minority religion who nonetheless requires external validation and a feeling of importance. And the main reason I see for not yielding to reality is suspicion that somebody, somewhere, may assimilate the young to a value system different from our own.