One of the central thoughts of Christianity is that God has revealed himself. This is true and we looked at it all to briefly and almost embarrassingly inadequately here.
The flipside of this truth is that while it is absolutely true that God has revealed to us his very self, it is also true that his very self is not fully comprehensible. We don’t understand everything there is to know and understand about God. God’s knowledge of himself is not identical to our knowledge of God’s self. Just as our knowledge of the world is not identical to God’s knowledge of the world. Or that God’s knowledge of my self is not identical to my knowledge of my self. Of course God knows and comprehends more and comprehends at a deeper more profound level.
But this is no cause for despair of course. Simply because I don’t know completely doesn’t mean I don’t know truly. It’s not as though this whole thing is purely binary – either I know everything or don’t know anything truly. This sort of extreme epistemological skepticism and relativism is goofy. I don’t really have the foggiest idea how an engine works. But I do know that it has something to do with pistons and with combustion. Just because I don’t know everything about modern engines doesn’t mean I can’t know anything truly. And it’s the same with God, and it’s particularly true if this God has revealed HIMSELF.
So while it is true that we don’t know everything there is to know about God, and we don’t comprehend everything there is to comprehend, and we certainly don’t know God in the same completeness as God knows himself, none of that necessarily negates that God has revealed himself truly in the person of Jesus and that we can know him truly.
We don’t comprehend him fully but we can comprehend him truly, and we can comprehend him truly because he has revealed himself.