“When the morally good atheist practices Christian morality better than many Christians do, he is not succeeding in being good without God. It’s God’s grace that’s helping him be good, even though he doesn’t recognize it or give God the thanks that is due to him for it. You can no more be good without God than you can see without light. But you needn’t notice the light when you see objects.
God is the source of all goodness. Moral goodness is like light and God is like the sun. You can see sunlight without seeing the sun, just as an atheist can know moral goodness without knowing God; but there can’t really be any sunlight without there being a sun, and there can’t really be any moral goodness, even in the life of an atheist, without there really being a good God who is the sole source and first cause of all goodness.”
1. Peter Kreeft, Making Choices: Practical Wisdom for Everyday Moral Decisions (Cincinnati: OH, Servant Books, 1990), 49. Print.