Holiday refers to holy days. That can be inclusive of any faith.  However, Christmas calls attention to Christ who is the reason for Christmas in the first place.  The entire reason for the celebration of Christmas is to celebrate Christ and so the word holiday leaves Christ out.  The green of the tree is for eternal life, the balls on the tree represent eternal as there is no beginning and no end. The stars represent the star that appeared to the Shepherds on that Holy night when Christ was born. The lights represent Christ the light of the world.  Who are we trying to kid when we settle for Holiday.  There is far  more than the greeting that those who hate Christianity need to seek  change. I of course think that Christmas permeates the world so much it cannot be stopped.