Atheists, if there's no God, how do you keep from assaulting people?

Without the the guidance of the Christian God, I'd be at a loss as to how to behave. I'd probably kick people in the groin, throw turds at their faces and then rape their pets. Luckily, my fear of God keeps me in line. Atheists, how do you keep from doing nasty things? You don't have God to scare you straight, so how do you do it????