The first flaw with the ontological argument is that it acts analytical, but in concept affirms a synthetic proposition. I talk here about the AOA. It adds something to an analytical statement, not concludes something from that analytical statement, which makes it a synthetic statement, but upon that grounds, it cannot be affirmed as it acts purely on an analytical basis. The other questions are simple: can we prove something's existence without experiencing it? Existence is a posteriori, and all proofs of existence have come from a posteriori notions. Then we get into the itsy bitsies of it: is existence perfection? This world is imperfect; hence God's existence would be a negation of His existence. Then we could go further and further and further: this necessarily follows from the nature of reason.