There is no such thing as anything, if you are a layperson.  Anything that you can sense or think of is a matter of belief, unless you are a scientist.  

You and I are Santa Clause to the scientist.  How else do you think he can afford the Santa Suit, liquor, wall-to-wall carpeting and little dog.  You don't earn that by simply sticking your finger in the electrical wall socket.  A scientist is given money to do important research like experimenting in electrical currents.

Just no Santa Claus. What's more interesting, is that there almost certainly was never a Jesus Christ. The man, endowed with or without the powers of a deity, never existed.

There is a museum in Antalya, Turkey that has a religuary with the bones of Saint Nicholas.

Please see 465 U.S. 668  and 492 U.S. 573.

In general, as adjudicated in the U.S., Santa is seen as a representation of the entire holiday citizen and NOT a specifically religious figure.