Well God is Omniscient so his mind is infinitely greater than ours so there is no way our finite minds can grasp the reasons for everything he does. Not until we have a better understanding in heaven.
Au contraire. Our finites mines are perfectly capable of grasping the reasons for what he does. He's a fictional character created by a multitude of other finite minds over hundreds of years, resulting in many different actions and personality traits that outright contradict each other. As a result, other finite minds that for whatever reason are invested in the idea that he's totally real try to reconcile these gaping character inconsistencies with the "mysterious ways" bullshit. It's basically the religious equivalent of "a wizard did it".
See? Perfectly graspable.
