No doubt we could say Santa Clause exists but we could not say that he exists as a physical entity in this universe. Since God must exist outside of the universe we don't really have any place to qualify where God exists.
Ok, so how does that answer the question, or make ANY sense whatsoever?
But just so I could shoot you down a bit...
If you were to say Santa Claus exists, then we could prove you wrong. The thing he is proposed to do, he does not do. We would have interviews with the parents who went and bought the presents, the children who saw Mommy and Daddy putting the gifts under the tree, and the cashiers at the malls who will all vouche that the only thing they ever saw Santa doing was ask for money, not buy toys.
The saving grace for your relgion is that your God promises a lot, but is very vague about when he'll do it. Aside from the occasional "After a thousand years" claim, it's all up in the air as to when these things would happen. He always made unproveable promises, such as curses that were terrible because they would affect someone's entire lineage, or the claim to Abraham that his line would live on for all time. So, basically, you get to walk around claiming all these terrible things, and no one can prove you wrong, because the time it was to take place hasn't passed yet. There hasn't been a Y2K for Christianity, so to speak, for your ludacris beliefs to be called out onto the carpet and proved wrong in front of the masses. (Though there are a few times in which semi-specific times are metioned and nothing happened; such as when Peter told his followers that the world would end during the lifetimes of some of those who heard him preech. Hmm...I'm here now, aren't I? And there are no apostles now, nor is there anyone who God is speaking to directly, or walking physically in front of, as there were in those times, but nobody notices.)
It's just too convienent that you can pretend to know exactly what you're talking about (99% of which you don't even get from the Bible; you make up yourselves) yet the second someone makes a point that you cannot defeat, you fall back on the nonsensical, stupid comments such as the one I quoted at the top of this post. The second you cannot sway us, you just talk bullshit. But even there you are swaying from the teachings; in the bible, you're taught to skip the swaying part, and go right to the bullshit.
JD *Edit was becuase I typed "YK2" in origional post...had to fix that one!*