Fanatics don't care about logic or common sense. They believe what a preacher tells them and usually won't question it. I may force them to decide that they're not completely convinced that they're views are right. Many people, deep down, aren't convinced their beliefs are right, and will back down if they think acting on those views will have consequences. Beliefs are taught to people. Knowings aren't taught.
Watch out for psychotic people, though - that's a whole other ball game. I avoid performing for them if I can. I don't want to fuel their illness.
Personally I resent that comment. I am a devout Christian myself (and a professional magician!). Keep your bigotry to yourself please.
Are you a fanatic? One can be a devout christian without being a fanatic, just as one can be a devout muslim without being a fanatic. If you are completely unquestioning, that is dangerous. That's almost a definition of the word 'fanatic', not a slur on the religious.
As I've said before, I don't try to convice people I'm for real as I consider that to be dishonest. Certain mentalists *cou-Uri Gellar!-gh* are similarly dishonest by consistently claiming to be the real deal. That's not going to help society progress.