In philosophy it has been pointed out innumerable times the many problems that the notion of (the hypothetical) God being omnipotent, omniscient and whatever-fancy-adjective-you-like-the-sound-of brings to the whole premise. But here's another one:
Is God perfect? The typical answer is yes, of course.
Does that mean that everything that God does is perfect? Again, very few theists would disagree.
Since God (allegedly) created us, and creating is doing something, and everything that God does is perfect, doesn't that mean that we, God's creation, are likewise perfect?
Now the contradiction starts to slowly dawn. If God is perfect, and everything he does is perfect, and we are his creation, shouldn't we be likewise perfect? Because if we are not perfect, that means that there's something that God has (allegedly) done that's not perfect.
If we are perfect, then how come we are able to sin? How come we are flawed? How can a perfect creation be imperfect in this manner?
If we are not perfect, then that means that God deliberately created something imperfect, and therefore not everything that God does is perfect. Therefore God is not perfect in all possible aspects.