For the same reason that theists only believe in their concept of god, all the other options failed to convince them for whatever reason. We just have a higher standard of evidence, and nothing in the entire pantheon of theistic mythology has managed to sway us. Frankly this is less a reflection of the diamond sharp analytical abilities of the atheistic and more a reflection of the woefully inadequate nature of the theistic epistemology.

That said, what I'd like to know is why other people actually believe this? If you were to find your holy text in a cereal box and read it in totality now, would you truly think it a divinely inspired text? Or is it simply an ancient perspective hangover that has not diverted enough attention to it's structure to warrant a full critical analysis?

I expected even more of a skew toward atheism than I saw here, actually.