Some people believe that the "Season" in "Season's Greetings" refers to specifically the Christmas season.. Some think it is an attack on Christmas it's self, while others claim that it is a commercially motivated term, created by card companies who hoped that the lack of a religious overtone would attract more consumers.
Still others think it is used to be more inclusive of all holidays celebrated in winter [though specifically Kwanzaa or Hanukkah].
Myself and others included, use it in acknowledgment that the receiver of the greeting may not be religious! That way, no one is offended if you use the "incorrect" holiday greeting. ^.^
SO, on that note:
~QOR