If humans aren't intelligent enough to understand humans don't make the best examples of anything but being a human. Then those humans have a reason to not want to believe. And it has [nothing] to do with what they see. It's how they view the idea of God from their own perspective. They will say God was mean in the O.T., or that God let's bad things happen to good people like it's only supposed to ever happen to bad people, they will use God doesn't make Himself known therefore He does not exist, they might simply just say God is about 10 commandments which equals RULES and I will not be ruled by anyone/thing but my self.
The majority of people have reasoned their disbelief way before having examples of fools failing to represent God correctly!