That depends, as the comment you replied to shows, on how they respond to that. I'm an atheist, but one of my wife's best friends is a dyed-in-the wool catholic

That depends, as the comment you replied to shows, on how they respond to that. I'm an atheist, but one of my wife's best friends is a dyed-in-the wool catholic, and we get on really well despite that fundamental difference. He has a great line in self-deprecating humour, where he talked about "going Taliban" during lent, of which he is very observant. Not all religious people - and, I would suggest, probably very few in fact - are nutters. They're just the loudest ones.