One cannot conceive of anything beyond their own understanding and experience.
Now there is a statement that was made by my Religious Instruction teacher as "proof of God"
50 years ago.
At the time, I thought is was garbage as far as proof of gods was concerned but could not quite say why. The religious, in their deep ignorance, are very clever at misusing words, definition and other tricks of language. The point is that the statement is either trivial or wrong.
We must first agree that if the statement were valid, then it does not point to any particular god.
Now we can say that if the statement is true, this proves that gods are figments of our imagination. The alternative is that a god is "within their own understanding and experience." However, this cannot be so, as it would mean that "ab initio" we knew of a god. It would not count if we were told, second hand, of a god by our parents.
A god is no more than a superman, a man who can do wondrous things that we can imagine, an animal that we can imagine with mystical powers, a strange combination of known forms that we can imagine, etc.
However, like the flying leopard that turns into a six-pack of beer when it passes lampposts, it does not mean it exists: in fact common sense speaks against its existence.
(edit to remove vestigial quotes)