Christmas has been taken over and subverted by Christianity. It's origins begin long before Judaism or Christianity existed, as early as 4000 B.C.E. when the Mesopotamians celebrated a twelve day festival known as Zagmuth. This holiday was held in honor of MArduk, the god of chaos, who they believed battled the monsters of chaos at the beginning of winter.
Later, the Romans held a celebration called Saturnalia which began in early December and lasted until the first of January. The Romans decorated their homes with garlands and put candles on trees in honor of the celebration. During this period, the Romans would visit each other and have grand feats and exchange gifts to foster good luck for the coming year.
The Roman celebration was probably the inspiration for the latter Christian celebration (as were many other Roman beliefs about god). Constantine, the first "christian" emperor incorporated the pagan holiday into Christianity with the hopes that Christians and pagans would celebrate the feast together.
Perhaps it would be more accurate to say "HAPPY SATURNALIA"!!!