Some have argued that a God whose essence is good is not worthy of our praise for doing good, since He cannot do otherwise. Being praiseworthy entails merit, but there is no merit in doing what one must do of necessity; therefore, God, is not deserving of praise for doing good.
William Lane Craig offers three points in response (Question #114) to this argument:
(1) While a good act must be free for it to be praiseworthy, this argument falsely assumes that since God cannot do evil, He is not free. Freedom, however, does not require the ability to do otherwise (in this case, to commit evil). It only requires that one’s choices are not causally determined by external factors. In that sense, God’s freedom to do good is a free choice. While God cannot do evil, He freely chooses to do good.
(2) Strictly speaking, “moral praise” is inapplicable to God. According to Craig, “Moral praise and blame have to do with duty fulfillment. Someone who fulfills his moral obligations is morally praiseworthy. But…I don’t think that God has any moral duties. For moral duties are constituted by God’s commands, and presumably God doesn’t issue commands to Himself. Therefore, He has no obligations to live up to. Borrowing a distinction from Kant, we can say that God acts in accordance with a duty but not from a duty. Because God is essentially loving, kind, impartial, fair, etc., He acts in ways that would for us be the fulfillment of our duties.”
(3) God is to be praised, not for choosing to do good, but for being good. As Craig writes, “I think that our praise of God for His goodness is…to be properly understood in terms of adoration. God is the paradigm and source of infinite goodness, and therefore we adore Him for who He is. We don’t offer Him moral praise in the sense of commending Him for living up to His moral obligations; rather we love Him because He is goodness itself.”