Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God?
All the seven deadly sins are man’s true nature. To be greedy. To be hateful. To have lust. Of course, you have to control them, but if you’re made to feel guilty for being human, then you’re going to be trapped in a never-ending sin-and-repent cycle that you can’t escape from.
What most atheists do believe is that although there is only one kind of stuff in the universe and it is physical, out of this stuff come minds, beauty, emotions, moral values- in short the full gamut of phenomena that gives richness to human life.
Julian Baggini, Atheism: A Very Short Introduction