(To be clear from the outset, I didn't write this. Robert M. Price did, in the 7th chapter of his first book.)
Once upon a Christmas Eve long ago, three precocious children were sitting around the fireplace. They were waiting for cobwebs to fill their little heads so they could retire to dreamland until the morning, when Santa would have made his rounds. The three boys were named Rudy Bultmann, Johnny Montgomery, and Franky Schaeffer. Having exhausted the conversational potential of baseball, tricycles and cowboys, their minds turned to theology. One of them looked at Rudy and said, "Rudolf with your nose so bright, won't you open our discussion tonight?"
Rudy began, "Friends, as you know, I have been asked to speak on the subject of Santa Claus. My response is 'Yes, Virginia, there is a Santa Claus,' but only in "Geschichte", not in "Historie", of course. There are many elements of the traditional Christmas story which are clearly mythological, and therefore unacceptable to the modern child. After all, can we really believe that anyone today would wear a red suit? And flying reindeer -- modern zoology and aerodynamics assure us that this is impossible! And where would Santa get all those toys? Surely, if he makes them in some North Pole workshop, he must be infringing on all kinds of patents! No child who has to go to a toy store and pay for a doll over the counter can possibly believe in a miraculous appearance of toys beneath the Christmas tree!
"Indeed, there may well have been a historical 'Saint Nicholas of Myra,' and he may even have been a charitable fellow. But all this about a 'Santa Claus' who magically flies around the world giving presents...! Surely this is primitive mythology! All the historian can document is the Christmas Morning Faith of the original elves. And, of course, what really matters is that Santa flies around in my heart!"
Johnny quickly became agitated, as he frequently did, and replied, "The trouble with you, Rudy, is that you don't give enough credit to the hard, historical facts! Look at the sources for our knowledge of Santa! They're just as good as the documentation for any other historical figure, maybe better! For example, take 'The Night Before Christmas.' It describes Santa's 'belly, which shook when he laughed like a bowl full of jelly.' Obviously, this kind of vivid detail is an internal confirmation of the poem's claim to have been penned by an eyewitness!
"Another thing, Rudy. You operate with an obsolete picture of the universe as a closed system of cause-and-effect. You assume reindeer can't fly just because you've never seen them fly. Why, you've probably never seen any reindeer period!
"And how do you explain the empty plate? We all know that kids put out a plate of cookies for Santa, and the next morning the cookies are gone! And don't give me that old argument that it was really the parents who ate them! Unless it was Santa himself, the historian can't explain the tremendous change in the Christmas tree! How else could all those presents have gotten there? It would be psychologically impossible for the parents to put them there. Why should they spend hundreds of dollars on those gifts just to perpetuate a myth? If Santa didn't really come it would be much cheaper to expose the deception!"
Franky chimed in, "Well said, Johnny! I can see that Rudy is making an upper-chimney leap. He thinks he'll end up on the roof, but really he'll find himself back down in the fire! All he's gonna get in his stocking is coal! Of course, the decisive argument against Rudy's position is that he can't really live on the basis of it. He inevitably finds himself acting as if Santa does come in space-time history. He wouldn't get up tomorrow morning and go look under the tree if he was consistent with his presuppositions. And besides, if Santa wasn't coming to town, Rudy would have no metaphysical standard to tell him he'd better not pout or cry! Actually, there's a dangerous cultural shift in this very direction. I can prove it by showing the gradual replacement of Santa by other motifs on recent Christmas cards!"
They decided to settle the question by staying up till Santa did or didn't come. So they all found good hiding places and settled down to wait. But, alas, the little fellows soon fell asleep. And the next morning, sure enough, the plate was empty and they all had presents.