Clarification on the issue of raising awareness in the ontological perspective

I have already read the notebook on ontological vision several times, and I have a misunderstanding regarding the similarity of the villain to the painter. I would be happy if the Rabbi could clarify it.
It seems to me that I can spare the painter all his work. He will only have to think of an existing painting, and then the painting exists! For in his mind there is an existing painting, and to deny this is only skepticism. The failure is simple: he cannot really think of an existing painting as long as it does not exist. He can only imagine the possibility of an existing painting, but this is not like someone who feels in his mind that it really exists.
So, even the villain can claim that he cannot conceive of God existing as long as he does not exist. He can only imagine the possibility of God existing, but cannot conceive of God existing. If so, the greatest being he can conceive of is precisely a God who does not exist.