Believing in God is about as realistic as believing the world is flat.
That is a bad comparison IMO. We have piles and piles of hard evidence the Earth is round. Saying the Earth is flat is just factually incorrect at this point.
But the existence of God. I would argue we have no hard evidence of God’s existence nor do we have hard evidence that God doesn’t exist. As far as science is concerned it is still a theory.
On top of that what makes a god a God there are multiple definitions of a God. If simulation theory is correct and we are all just in a simulation would be people outside of the simulation be our Gods? Or if an extremely advanced civilization existed would they be Gods to us? Or If we as humans advanced enough could we become Gods our self.