This whole kerfuffle about when and where religious expression is appropriate is, IMO, a manifestation of the increasing religious diversity in the US. When I was in school quite a few years ago, much of the US was religiously very homogeneous. "Diversity" was Catholic or Protestant. Christmas carols and Bible stories in school were not uncommon, and no one thought anything of it that I know about. Is that right or wrong?

I would hazard that in this day and age with religious diversity it might be appropriate to discuss (in a class called "Comparative Religions", say) the differences among cultures how their religions work, what holidays they celebrate, etc. The big problem seems to be fear: i.e. if one religion is discussed, does it "invalidate" all others?