I only believe what I can see
Then you are a very mislead person.
People always say, "I won't believe it unless I can see it, touch it, smell it, etc.", but if that is all that is required for something being "real", then real is merely electronic signals being sent to your brain. And those can be easily fooled, tampered with, and it's a very poor definition of real.
I'd say an outside source of which the effects are not only tangible yourself, but also by others and has a clear effect on your living enviroment and is logically consistent, whether it's an electrical signal or not, is far more credible than the electrical signals you yourself input in your brain, without any other tangible outside source, who's very existance is already in conflict with base physical principles.
Also, who believed in any god BEFORE he "witnessed" an event to lead to the existance of such a god.(as in, creators of a religion, such as Abraham or Muhammed) If Jesus wouldn't have performed any miracles, then there would be no christianity. Quite sorry, but the very existance of most modern religions are based on a visible and tangible situation that was created by a godly force. You're saying Kleaver is mislead because he only believes what he sees? Religion was based on visible miracles that couldn't immediatly have been explained, other than by a god.