3. As God is His own being, nothing can be said of God that signifies participation. If therefore evil could be predicated of Him, the predication would not signify participation, but essence. Now evil cannot be predicated of any being so as to be the essence of any: for to an essentially evil thing there would be wanting being, since being is good.* There cannot be any extraneous admixture in evil, as such, any more than in goodness. Evil therefore cannot be predicated of God.
5. A thing is perfect in so far as it is in actuality: therefore it will be imperfect inasmuch as it is failing in actuality. Evil therefore is either a privation, or includes a privation, or is nothing. But the subject of privation is potentiality; and that cannot be in God: therefore neither can evil.
This truth also Holy Scripture confirms, saying: God is light, and there is no darkness in Him, (I John i, 5) Far from God impiety, and iniquity from the Almighty (Job xxxiv, 10).
1.38 : That God is His own Goodness
1.40 : That God is the Good of all Good