As far as I've always heard, God is besides omniscient also omnipotent, which means he can do anything, but please correct me if I'm wrong.
I don't get it, God did create us in his image, didn't he. So if he cannot do anything against his nature, why can we do things against his/our nature. Or did he create us with a different nature? Why did he create us as sinners than? Isn't it against his nature to create something that can act against his nature?
It's the question of the chicken and the egg. You say that nothing can come from nothing, but in the same sentence you state that God was the origin and therefore always was and therefore does not need a cause. This is circular logic, if every effect needs a cause, so does God, unless he was created by God's God.
The problem with believing in God is, that God must be the answer to everything, but he isn't. While a non-believer can simply say, I do not know.