When someone reads about Dorothy being blown into the land of Oz by a giant tornado, we accept that in this other place there would be munchkins, flying monkeys, and witches names after the four primary points of the compass.
When we read about four children transported to Narnia we are perfectly fine with talking animals and other mythical creatures living in this other place.
But when we consider God we often fall short because we fail to embrace this sense of otherness. God is not like us. He is different enough from us to have been able to create us and the world we live in, simply by the power of His spoken word.
Everything we interact with in our place was created for us by God. This by itself implies God must be wholly other, totally different than us.
So placing the constraints we live under on Him, is nonsensical. When people say things like, “you cannot be three and one at the same time,” they are failing to give God the necessary sense of otherness. What is hard about this sense of otherness is it is a totally open set. We know some things about what God is like, because He has told us. We also know a quite a few things about God where He told us what He is not like.
The goal of theology is not to know everything about God. It is the goal to know Him personally, experientially. But the leap of faith many people struggle with in understanding God is allowing this sense of otherness.