The celestial Santa Claus hypothesis is so unlikely to be true that it should be dismissed as an option until further evidence presents itself. To cast this into policy would make this easier to move to higher definitions of truth with actual objects attached.
God doesn't exist. They are encouraged to worship something that references nothing. This is the essence of idolatry, which the Bible forbids. So from a biblical perspective, at least Judaeo-Christian religions should be banned.