Could be the heaviest theological question ever. There are as many ideas on the origin of evil as there are people pondering the question. The general consensus: We don't know!
It is said that "Fools rush in where angels (or wise men) fear to tread." That being said, I hope at least to be a "fool for Christ."
Please bear with me while I define my terms. I'll get to the point, I promise. Will you agree with my point? No promises.
We are created in God's image. We model some of his character traits: creativity, ability to express love, desire for relationships, self-knowledge or awareness. There are others, but you get the idea.
This self-awareness (God's covenant name is I AM) in humanity is something that has been on my mind.
Here in the Reformed neck of the woods, we hold to God's sovereignty. God is autonomous; self-existent.
In man's case, it would seem that self-realization ("I think, therefore I am"), carries with it a drive toward autonomy ("you will be like God"-Gen 3:5b).
Autonomy is from the Greek (autos self; nomos law). Here is a definition from the redneck dictionary: auto-no-my or "No! My Self!
Were Adam and Eve created "very good?" Yes. Did God foresee the fall? Yes. Is God the author of evil? No.
It would seem that self-awareness carries with it the desire for self-rule (Lucifer, right?). I've seen it described as a vacuum. Or maybe a law of moral physics (every action has an equal and opposite reaction). In other words, the very existence of good (God) may explain the existence of evil.
Like I said, heavy stuff. Here's what I do know: as far as personal evil is concerned, I don't have to look far to place the blame. It would be comforting to say, as Eve and Geraldine did, "The devil made me do it!"
But I am aware of a "desperately wicked and deceitful heart (Jeremiah 17:9) and like David, "my sin is ever before me (Psalm 51:3b).
Where DID evil come from? Here is a better question: "Who will rescue me from this body of death?" (Romans 7:24b) Paul's answer: "Thanks be to God-through Jesus Christ our Lord!" (Romans 7:25)