Originally Posted by The Unfan

Perfection would require that God is both all knowing and all powerful. This would require that God knows everything that will happen ever and have the ability to do anything he wants. If God knows everything he knows what he'll do next. If he were capable of changing his mind he wouldn't have true knowledge of everything, on the other hand if is he is incapable of changing his mind than he lacks a power and is not perfect. Since it is impossible for him to both know everything and do everything he is not perfect.