I think a couple of you have really missed the point on this Santa example.
Santa himself is, I think I can fairly say, a magical figure that would exist within our reality. A god on the other hand can exist outside the boundaries of known reality, can transcend space and time,
Santa would need to transcend space and time, or be able to exist outside the boundaries of out reality, to be able to do all his deliveries in a single night.
purportedly the creator of all existence, and the existence before existence, existing itself outside of the everything and the nothing.
Bolded the important bit here. People claim many things.
I don't think the Santa analogy is all that bad. He is an all-seeing father figure, who will reward you if you are good, and punish you (albeit in a much lighter way) if you are bad. He also has mystical lackies. He accepts offerings in his name (milk & cookies), and only a handful of people ever claim to have been in direct contact with him. He also doesn't seem to do much for those in this world that lead an impoverished life.
Then you look at the cultural differences in the Santa myth, and it seems pretty similar to all the varying religions you get. Sometimes you get a single head honcho type, sometimes you get Yulemen, a sort of pantheon-esque version like Olympian gods.
I'll say one thing, human beings in general have a pretty cool imagination sometimes.

Fixed your bold text - Gilly