I think what happened was is that he is basically prejudice against religion and some other things, like some people are against blacks, gays, etc... Eeems mentioned something about it to him, and he blew up on it.
From what I've seen, if there is something on the site that he doesn't like, he thinks everyone, or a large majority of people, think the same as he does, and he acts out against it as much as possible. Remember the MLP thread a month or so ago? He blew up at that and even threatened to leave until the thread was deleted/locked, just because he assumed that every single person shares his views on MLP.
TL;DR: He's just very close-minded. He seems to think that everyone else is either just like him, or the enemy, and therefore must be purged.