"No one stays good forever"

[Weltall]

Along similar lines, the judeochristian god, as depicted in the Bible, is a lot like how you described the fearsome image of Superman in Batman's head: a being which has essentially limitless power and abilities, yet lacks emotional maturity and empathy, and therefore does awful shit like slaughtering all the first borns in Egypt because their unelected ruler was being disagreeable, or drowning everyone and everything on earth because some people were misbehaving. That sounds like the most horrifying sort of megalomania and psychopathy. The god of the Old Testament and Jesus hardly seem like the same entity. As the dogma has it, God is right and good even when he does things like that because if he commits genocide, it can only be because his victims deserved it.

However, if you instead view god as an entity who has powers he barely understands and is attempting to learn how to use them (with no help or instruction), god is not a crazed, bloodthirsty tyrant but a child trying to learn. Children can do cruel things, but usually stop once they grasp the concept of cruelty. It would explain the profound difference between the Testaments, and makes god's behavior not just understandable but relateable.

Unfortunately, his believers are far too insecure to accept such a notion.