Everyone else has pretty much already said it for me. It's just the whole sense of superiority, the barely-unspoken "keep going, you'll come to The Truth™ one day!" that does me in. That and the "pity poor persecuted me" thing.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'