Neil Gaiman was irritated to learn his beloved C.S. Lewis was a Christian who infused his work with Christian truths. He felt betrayed that this favorite author would have an agenda for his stories (as if all authors don’t write from some kind of moral framework), but Lewis’s influence on Gaiman carries on. Russell Moore spells in out in Touchstone.
In the American Gods mythology, the old gods—the supernatural beings associated with rain and fertility and war—are at odds with the new gods—such as media and technology. Many of the motifs of Narnia are there. The “bad guys” muster their troops at the Stone Table in Lewis’s Narnia; they do so at Chattanooga’s Rock City in Gaiman’s America. The Pevensie children find their destiny as kings and queens of Narnia; Gaiman’s human Shadow Moon (yes, that’s his name) finds his destiny as, literally, the son of a god. Aslan offers up his life as an atoning sacrifice in Narnia; Odin does the same for Gaiman, complete with a spear in his side and, of course, a resurrection.
Gaiman would say that he is simply working with the myths as he found them. As he retells the story in his recent collection of Norse myths, Odin does indeed climb the world tree and hang himself in self-sacrifice, “making the world-tree a gallows and himself the gallows god.” For Gaiman, the gospel might well simply be an echo of that archetypal story. One god with the gallows, another with the cross. But, of course, that is precisely what initially repelled Lewis from Christianity, and ultimately drew him to it.