I thought I'd type this up here and see what everyone thinks. It has most of the parallels you'd expect, although some are missing. Please discuss.

 In George H. Smith's book Why Atheism?, he tells a story of two kids. The younger child (Jack) believes in Santa Claus and defends Santa vociferously in the face of his sister Jill's Santa-Atheism.

Jack, a precocious six-year-old who wants to be a theologian when he grows up, has just been told by his older sister, Jill, that Santa Claus does not really exist. Little Jack is dismayed that his own sister-who had long shared his passionate belief in the existence of a being than which nothing jollier can be conceived-has joined the ranks of skeptics and blasphemers, so he resolves to save her from the torment of never receiving another present on Christmas morning.

"How can you possibly claim that Santa doesn't exist?" Jack says to Jill. "Just look at the evidence. First, our parents, neighbors, teachers, and other adults have assured us of the existence of Santa, and we have no reason to suppose they have lied to us. Plus, I get presents every Christmas that are personally signed, 'From Santa,' and he drinks the milk that we leave out for him. What are you-some kind of conspiracy nut who believes that the entire adult population is out to deceive little kids? Second, my letters to Santa (which I address to the 'North Pole&#39 have never been returned by the post office, so what happens to them if they don't go to Santa? Do you expect me to believe that the United States government is part of this vast conspiracy of yours? And what about the news bulletins every Christmas Eve that track the movement of Santa's sled? Is the media also part of this global network of deceit? Am I to suppose that adults are so determined to lead kids astray that they would fake all this evidence? Thus, if I am to believe you, if I am to believe that Santa does not exist, I must reject the testimony of competent witnesses, ignore the evidence of my senses, and-worst of all-I must become a conspiracy nut who believes that parents, teachers, politicians, journalists, ministers, and countless other adults have nothing better to do than to participate in a nefarious scheme of deceit. All this strikes me as highly improbable, so I must logically conclude that Santa does in fact exist."

Smith, George H., Why Atheism, pg 64-65, C2000