The existence of evil is most commonly explained as a consequence of free will. This is consistent with the biblical idea of the Fall of humanity. God gave humans the ability to make their own choices, and that means that he cannot prevent us from acting badly. However, most theists also want to say that God knew ahead of time what his free creatures were going to do – and thus knew we would be sinful.
Now, on the standard view, some free-willed beings do not ever choose to do evil. There’s at least one who doesn’t, God himself – though on the Trinitarian view, there would appear to be two other sinless personalities. Whatever the case may be, the theist must admit that it is at least possible for a being with free will to never do wrong. And even if the theist comes up with some excuse for why this applies only to God, and not to created beings, the fact remains that some humans are a hell of a lot worse than others. Most of us would not and could not ever do what, say, Charles Manson did. And some of us are far more moral than the average.
It follows that God could either have prevented all of the evil that his free creatures have done simply by creating only ones who would never chose evil, or, at the very least, that he could have prevented just about all of that evil by creating only highly moral beings. Either way, there’s no excuse for most of the evil out there.
[Originally published at Debunking Christianity]