I think the main fault of very religious people is that they have no sense of humour. I mean, if god created man in his image then he must have one hell of a sense of humour, and would he then mind a few good jokes at his expense?
And furthermore, would Jesus and Mohammed have reached such popularity if they didnt know how to make their followers laugh a little. Jesus probably told more than one "A Pharisee walks into a bar.." joke in his time.