God is the one supernatural thing seen as something you should be a moderate believer in. Apologists, especially with in-your-face atheism becoming in-style, try to play off the option of not-believing as if it's a reactionary and rash choice made without considering all the options. Maybe parts of the Bible aren't literally true. However, you'll never see an adult arguing for a moderate belief in Santa because parts of the Xmas mythos could be taken as metaphorical or poetic.
Perhaps there's no literal workshop or sleigh, but without Santa's list you couldn't be moral!