I think it's more that we don't really consider religion a suitable topic of conversation in most circles.

I can see where you're coming from. But, as personal as religion is for some folks (and the ones that wants to keep it to themselves, that's completely ok by me), when that religion is affecting other people - and this is mostly in a negative way and mixed in with politics :P, then I don't see the problem with talking about religion in a social forum. Religion does not deserve to stand above discussion, be it a debate or a friendly exchange of ideas/beliefs etc.