Well, if you can't prove he didn't exist then stay out of it. You're a skeptic, you obviously bring it up because you refuse to believe anything the Bible says and dismiss it as "fairy tales". You can have your opinion but don't bring up bullshit if you aren't gonna prove it.
Edit: I apologize for going overboard a bit. Seriously though, there's no factual or undeniable evidence about alot of stuff. If it was all factual and undeniable there'd be alot more believers. You tell me, whats the point of faith, if God wanted EVERYONE to believe in Him, don't you think He'd make us all believe. No, that's not His plan.
http://www.carm.org/uni/allmensaved.htm
That link may sound like what I said is wrong but I said that in a matter pertaining to the main idea, being that undeniable facts be the deciding factor for everyones faith. Which would eliminate faith. Not to mention that everything around us is God's creation, therefore there's no excuse, unless it is not in his will.