I answer that, As shown above (FS, Question [29], Article [1]), hatred is a movement of the appetitive power, which power is not set in motion save by something apprehended. Now God can be apprehended by man in two ways; first, in Himself, as when He is seen in His Essence; secondly, in His effects, when, to wit, "the invisible things" of God . . . "are clearly seen, being understood by the things that are made" (Rm. 1:20). Now God in His Essence is goodness itself, which no man can hate---for it is natural to good to be loved. Hence it is impossible for one who sees God in His Essence, to hate Him.
Moreover some of His effects are such that they can nowise be contrary to the human will, since "to be, to live, to understand," which are effects of God, are desirable and lovable to all. Wherefore again God cannot be an object of hatred if we consider Him as the Author of such like effects. Some of God's effects, however, are contrary to an inordinate will, such as the infliction of punishment, and the prohibition of sin by the Divine Law. Such like effects are repugnant to a will debased by sin, and as regards the consideration of them, God may be an object of hatred to some, in so far as they look upon Him as forbidding sin, and inflicting punishment.