All moralities, chimpanzee politics, are based on axioms (unprovable assertions) of right and wrong. Such axioms cannot be discerned through reason. Reason is used to put them into practice and to iron out contradictions in the use of those axioms. You may use reason to act consistently on your own beliefs - but where do those beliefs about good and bad come from? In short, either you accept God's moral axioms, or you come up with your own. But a lot of people (seriously, like Stalin) came up with some moral axioms that clashed seriously with God's axioms. Having to choose between axiom sets, I have much more faith in God's than in my own. When you choose your own axiom set for your own morality, you make yourself your own little God. It's like a father who says to the son - these are the rules of the road - whatever you think, son, the following things are good - being polite to your mother, staying off of drugs, not making babies with women you're not going to spend your life with, taking care of and protecting your younger siblings. But the son says, well - I'd like to define my own right and wrong. I don't think it's bad to be impolite to my mom, I think it's good to get hooked on drugs, I don't care whether it's good or bad to get girls pregnant (because I don't care about the potential human life I might create) and I don't care about my brothers and sisters. Now, can you imagine the punishment that son will get?