I'm sorry, I thought we were talking about proving that God was invented by men, not that religion was invented by men. The two are not equivalen in this scenario. I continue to await your proof.
All religions were invented by man. Religions are what predominantley lead people to believe in God. The large majority of beliefs in this world today was invented by different men.
The next part is trickier, because no one knows for how long before they wrote about it people started thinking about higher powers. If they wrote about, they thought about it, and the idea must've been a function of cognition. Now you could say that God talked to these people or inspired them to think of these things, but there is no historical (religious texts are far too biased too count) evidence of these things happening and you could also argue that all ideas - including Grand Theft Auto: Vice City and Atheism are inspired but God, but there is no reason to believe that they were.
You could also say that the events described by Scientologists happened too, but there is no evidence that they did or that L. Ron Hubbard is really a prophet (there are several "prophets" on the streets of any city you can name).
Religion is defined as "belief in a higher power" and we can first trace back to the Ancient East, where Conficious and Buddha lived, men, who wrote about Tao and Buddha and whatnot (not compatible with each other or traditional Abrahamic God) -- this is history and these are men.
Many people, as demonstrated by this site, take the fact that the earth is round on faith... Therefore, by Ubuntu's Funnel, the earth cannot be round.
Actually we look at photos, videos, read about astronauts, space programs, study science and astronomy... logical proof and material evidence. (Even if someone were fooling you by providing false material evidence -- a clone of your dead spouse, say -- the conclusion you come to would not be illogical.)