I, too, am an atheist & I think that you would have a very hard time trying to prove that Jesus did not exist. There are not a lot of references to him & that is partly because the Rabbis of the time thought of him as a rebel (which he was) & a criminal, who undermined their authority (which he did), so they did little to push his agenda.
I do believe that JC lived, but I am undecided whether he was the leader of a rebellious group or he was the dupe who took the blame for everything. JC & his little band did everything they could to convince the average Jew that he was the son of God & it may have worked a little too well for him. The people were expecting a Messiah & I don't think it was that hard to give them one based on the hard times they were living in.
Allan