Rational: At present, the hypothesis that god exists is beyond the realm of scientific inquiry; that is, no experiment can be designed to accurately test the hypothesis. In other words, there exists no evidence that proves god's existence or non-existence. Thus, both atheism and theism are both quite literally "leaps of faith." Personally I find no reason to make such a leap either way since I have things that I would rather do with my seemingly finite conscious time on Earth than contemplate the unknowable. That is, Thinking about religion is a waste of time since I have people to see and places to go.
Economic: Religion in the US is a $multibillion / yr industry. Just think, we could channel those $ into other meaningless consumer-driven endeavours.
Musical: Christian rock is just screaming for a counter-culture; well, not literally...
Sexual: Almost all religions hold some "practices" immoral. I'll type some dots to indicate the limitless possibilities...
Criminal: Remember the crusades? That whole "I'm impaling you in the name of religion" thing just won't cut it anymore.
Medical: Good-bye Christian science and all its crazy derivatives.
Democratic: Let the people choose! (I have always rather appalled the whole I have to be the religion I was born into deal.)
Feminism: In the Apathetic Agnostic Church, we don't have time to care about gender bias.
Moral: I offer you this poem I wrote in high school: