It always amuses me to think how archaeologists in the distant future would be surprised to discover evidence that the inhabitants of Australia, New Zealand and South Africa celebrated a midsummer festival that featured an elderly gentleman dressed in furs suitable for wintry weather, riding a sleigh pulled by an alien species of deer; when people exchanged cards depicting unseasonal snowy scenes populated by alien fauna and flora. It would not be hard for the archaeologists to deduce that this was clearly a cult imported from the nortern hemisphere, but they might wonder why no attempt had been made to adapt it to local conditions. (My suggestion would be Santa Claus dressed in beach gear, arriving on a surfboard, perhaps with attendant dolphins)
Every year we hear of primary school teachers getting into trouble for telling their little charges that Santa Claus doesn't exist. It think this is quite right: after all, these days Santa Claus is probably the only supernatural being some children are brought up to believe in. He is an ideal icon for the present age; his entire raison d'etre is consumerism (where would shops be without him, and the obligation to buy presents?), and he contains no trace whatsoever of Christianity, being therefore equally suitable in our multi-cultural times for Moslems, Hindus and even atheists. His cult embodies the famous schoolboy definition of faith: believing what we know to be untrue; so adults pretend to believe in Santa Claus for the sake of their children, and the children, once they have reched a certain age, pretend to go along with it.
It is significant that in the old Soviet Union the Communists managed to scap most public aspects of Christmas, but they never managed to abolish Santa Claus, who was reincarnated in the transparently thin disguise of "Grandfather Frost".