It is not merely Christ, divine son of God, that is an article of faith, but also the so-called "Jesus of history". A liturgy of carefully crafted "proofs", a hallowed parade of alleged witnesses, and a handful of dogmatically interpreted writings are the sacraments of this faith.
But what better explains a thousand different Jesuses than the single word: fiction
Was Jesus, like Alexander the Great or Julius Caesar, a real historical figure to whom legends and myths became attached? Or, rather, like Huckleberry Finn or Sherlock Holmes a purely fictional character, passed off as a genuine personage or later historicized by other hands?
Perhaps the choice is not quite so clear cut: a person (perhaps several) were certainly in the mind of Mark Twain and Sir Arthur Conan Doyle when they constructed their heroes. Twain drew inspiration from his own life. Doyle modeled much of the character of his detective on his own professor of medicine, a Dr Joseph Bell. Did that make Sherlock Holmes any less of a fiction? (Interestingly, Holmes's trademark deerstalker hat is never mentioned in Doyle's stories and the drop-step pipe was the contribution of actor William Gillette years later. That's how myths grow.)
With Jesus, most people feel more comfortable with the 'historical kernel' approach. It is intuitively satisfying to think that someone was behind the towering legend. We do, after all, have Christianity, and it is hard to give credence to the idea that someone "just made-up" Jesus Christ and then managed to convince anyone else to believe that he had lived and died. In fact, one can reach the conclusion that "there must have been a Jesus" without any research at all, which of course is what most people do.