You're saying they didn't know that if you dropped something it would fall? That's a silly notion. Of course the Greeks knew about gravity. They didn't know what it was, and they certainly weren't able to quantify it, but that doesn't mean it did not exist.
No argument from me here. I've said all along that you cannot prove a negative. I've never said that gods cannot exist. I've only said there is no evidence that they do and therefor no reason to believe that they do. There's no evidence that Neverland doesn't exist either. That doesn't mean Peter Pan will be dropping by tomorrow.Absence of verifiable evidence is insufficient to conclude something is false. You'd need to be able to show its negation is verifiable to show anything about the truth of the existence of God.
You misunderstand! I don't have to prove that he doesn't exist! Again, such a proof is impossible. If you want people to believe he does exist, then it's up to you to provide proofs of that existence.It is perfectly fine to assume God does not exist for the purpose of doing science, and that's a perfectly rational position to take. However, it is not a proof, so you have not done enough to show the public that god does not exist.