Aaron: Imagine, if you will, a world in which God does not exist. In such a horrible place, people would be without moral control — without spiritual guidance. Our society, on the other hand, has a morality which even you, an atheist, subscribe to.
You: Do you mean that God tells us when we do something wrong? I certainly don't remember him telling me any such thing.
Aaron: No, no, no. I mean that, because we have God's example to show us what is good, we can avoid that which is evil. If we did not have God's example, then good and evil would be indistinguishable to us.