This paper elaborates and defends an argument for saying that if God is necessarily good (morally perfect in all possible worlds), then He does not have the maximum conceivable amount of power and so is not all-powerful. It considers and rejects several of the best-known attempts to show that necessary moral perfection is consistent with the requirements of omnipotence, and concludes by suggesting that a less than all-powerful person might still be the greatest possible being.

Great is your power, and your wisdom is immeasurable. Psalm 147.5