Argument from apologetics
The argument from apologetics is a variant of the argument from existence of atheists:
If God exists, there should be evidence for this. If theology is a valid field of inquiry, then there ought to be good, nearly universally accepted arguments for the existence of God. Since there aren't, it is more reasonable to believe that God does not exist.
It is widely accepted among theists that there is no physical evidence for the existence of God. (A notable exception is the Argument from design.) One apologetic is that God wants us to believe in him on faith alone. However, this is an untestable assertion: it might be true, or it might merely be an excuse for the lack of evidence.