So Politically Correct we can't talk?

[The Professor]

I guess I'm not sure why an inclusive greeting between people who (a) may not share the same religious affiliation and (b) may not know each other's degree of religiosity or affiliation is a bad thing. Why is defaulting to a greeting that's inclusive rather than exclusive bad? I say "happy holidays" all the time and don't really understand why the email referenced in the OP is bad at all. Seems like a pleasant and thoughtful fellow, if you ask me.