Claiming You Have to Be God to Know if God Exists

I believe there is nothing that can convince the atheist or agnostic in God, because no matter what God does, the atheist or agnostic rationalizes it away in their flesh somehow, no matter how ludicrous. Not even a parlor trick would convince, which would be unethical for God to perform anyway. Basically, the atheist or agnostic is claiming he has to be God to know if God exists, because even if there was one last thing the Atheist or Agnostic didn't know, he would still be special pleading by holding out maybe this one last thing could prove God doesn't exist, despite the overwhelming preponderance of evidence of trillions of causes and effects in nature requiring a cause for nature, so that it just can't happen all by itself.