"If one does not believe in God, how do you know the difference between good an evil?" Conscience is a product of evolution, as is some sense of morality.
"I truly believe that man is a selfish, self centered being at his core" Christianity is the only religion to do so. It's a scare tactic to subjugate the idiot masses. Ironicaly enoungh, this means that christianity's main doctrine lies not with the incarnation of jesus, or even the sacrificial atonement, but with original sin.
"If you do not believe in God, why not rob, steal, kill and so forth to make your time here on this planet as pleasant for yourself as possible" Because these things are stupid and unethical. One can be moral without god, and still 'have a good time' so to speak.
"After all, there are no permanent consequences for your actions" Again, one does not have to believe in eternal punishment to realize there are consequences for immoral acts.
"No Heaven or Hell.....so why not?" Because, unlike you, we don't do those things simply because they are wrong. We don't need to be promised of eternal reward (which is the highest form of greed, a cardinal sin) in order to know that it's just good to do good, and bad to do bad.