the mystery of God's sovereignty and the existence of evil

I really appreciated this attempt to verbalize the mystery of God's sovereignty and the existence of evil.

God doth not will [sin] directly, and by an efficacious will. He doth not directly will it, because he hath prohibited it by his law, which is a discovery of his will; so that if he should directly will sin, and directly prohibit it, he would will good and evil in the same manner, and there would be contradictions in God’s will: to will sin absolutely, is to work it (Psalm 115:3): “God hath done whatsoever he pleased.” God cannot absolutely will it, because he cannot work it. God wills good by a positive decree, because he hath decreed to effect it. He wills evil by a private decree, because he hath decreed not to give that grace which would certainly prevent it. God doth not will sin simply, for that were to approve it, but he wills it, in order to that good his wisdom will bring forth from it. He wills not sin for itself, but for the event. (Stephen Charnock, Discourses upon the Existence and Attributes of God [Grand Rapids, MI: Baker Book House, 1979], 148.)

borrowed from John Piper, Spectacular Sins