Symbols of Paganism and Christianity? I challenge thee to find even a single example of a religion that claims the modern day Santa Clause as its own.
Though the origins of St Nic may or may not be in Christianity i assure you the commercialised fun fest we know and love as Santa Clause's christmas has no affiliation with Christianity whatsoever. Christmas to the Christian is about the birth of Christ. Whether or not a parent buys into the 'moral message' of santa clause is each to their own.
Oh dear. Just a quick read of the wiki page on santa shows just how wrong you are.
Santa, St Nicholas, Father Christmas or whatever you wish to called him has his origins in early pagan and christian symbolism. The commercialisation of christmas is a separate issue.
http://en.m.wikipedia.org/wiki/Santa_Claus?wasRedirected=true