"[I]ndeed, mere fantasy deceives the mind and, through passion, causes vain attachment to objects that do not exist, but provides no foundation in reality." (Ad Thalassium 64)That's from a translation by Paul Blowers in the collection, On the Cosmic Mystery of Jesus Christ from the Popular Patristics Series. There's also a footnote that says, "Cf Gregory of Nyssa's famous dictum that man 'invented' evil."
I'm not sure I agree with that exactly, but I do think evil must be in a different ontological category than good. God created light, then separated it from the darkness. He did not create the darkness.
The existence of evil is an eternal puzzle, but one way to explain it is as a perversion of something, for which I cannot find the right word, which must necessarily exist. Perhaps I'll call it "non-existence" or nothingness. Existence needs non-existence. Light needs dark. But there are good and bad ways for this nothingness to exist.
If light existed without darkness, there would be only light and nothing else. But in that case there would really be nothing. A pure unitarian existence is no existence at all, because such an existence cannot differentiate between something and nothing.
Since everything which is both important and true about God must be stated as a paradox, I would not hesitate to say that God's existence is both absolutely necessary and dramatically contingent. The threat of God's non-existence is precisely the drama that unfolds in His trinitarian union. God the Father does not want to lose God the Son, and vice versa. Whatever else love is, it means desiring the continued existence of the other, and if that is to mean anything real, there must be a genuine threat to that existence.
Indeed, that genuine threat is played out in the drama of creation and, ultimately, in the cross of Jesus Christ. God actually died. To say otherwise would be to deny the greatest mystery of the Christian faith, And a tremendous corollary: the Father actually lost the Son. In this drama, God's love is proved more real than it ever could have been otherwise. The threat of nothingness was so real that it was actually fulfilled.
This drama is played out in all of creation. Why, I asked earlier, would God risk creating a world which is capable of producing evil? Because such is the only kind of world that can genuinely exist. And in our world the threat is so real that we see its fulfillment on a daily basis. We see nothingness win over existence. We see chaos triumph over order. We see creatures separate themselves from their Creator.
The difference between us and God is that we do not use nothingness in support of existence, death in support of life. Our pain becomes suffering because we experience it in isolation. Because we make our existence entirely our own, any threat to that existence becomes a threat to our entire universe. That is what evil is.
But God does not let nothingness turn into evil. As the psalmist writes, Even darkness is not dark to you, the night is as bright as the day. When God died, when God lost God, He raised Him up from the dead. In dying He defeated death; in not existing He showed that He truly exists. As Jesus said, Those who find their life will lose it, but those who lose their life for my sake will find it.
Which means we always have the chance to become like God. Instead of wanting to be free from the drama of existence, we ought to embrace it. Life is risky; everyone knows that. The source of eternal life is not the elimination of all risk, but rather than paradoxical joining of the absolute assurance and the total uncertainty of our future existence--and not just our own, but that of everything else, as well.
I don't think this "lets God off the hook," so to speak, for terrible things that happen. He could have intervened, so why didn't He? If we love God, this question will come up again and again. To stop asking it would be to deny the essential drama of life, which is that paradoxical union of God's presence and absence.
So it is not about coming to God's defense, but rather finding the way forward which concerns me most. If we have lost, let us mourn that loss. If we have gained, let us rejoice in that gain. Either way, let us always desire life all the more. Not a monotonous, stable existence which is equivalent to nothingness, but rather a dramatic, risky existence which never ceases to puzzle the imagination.