I'm not a big fan of abbreviations in general, but there aren't any other Xs around and the timing was perfect!.
The abbreviation XMAS for Christmas dates back to the sixteenth century. X is the Greek letter for Chi, the initial in the word Christos or Christ.
As knitters we are familiar with Xs, too, in lovely textured cables.
XOXO! And Merry Christmas.
Brrrr! It was so chilly when I went out to take this picture I completely forgot to turn around and get a shot of the wreath and garland-draped gazebo!