We need to use "Xmas" more. We owe it to our heritage and legacy.
A year ago, I suggested that representatives of my own group are barking up the wrong tree when we vehemently demand the replacement of the letters "Christ" back into the culturally-preferable "Xmas."
I'm not finished. We're shooting ourselves in the foot and protecting Jesus (who can protect himself just fine) instead of his message (with which we've been entrusted).
The "ΧΡ" (the first two letters of "Christ" in Greek, Χριστος), has been a symbol for Jesus for so long. Perhaps it was even the first symbol. It's still employed in many places by Roman Catholics, Protestants, Orthodox, and Anglicans alike. It is a thoroughly acceptable identification and expression of faith to represent Christ.
They call it "Christmas" in "Frosty the Snowman" and "Rudolf, the Red-Nosed Reindeer," yet there is no credence given to the Christ. It is merely a word, a name for a day. So the X itself can make it very clear that "Christmas" is not merely a *word*, but refers to a specific important individual, X, whom everyone should recognize by that ancient symbol. When we use it, the X, ironically, makes it clear who we mean, where "Merry Christmas" becomes a buzzword that gets lost in the mumble of the marketplace.
"I really wish more stores would take Christ out of Christmas to distance Him from over-consumerism." --Don Miller
Also, since the X has furthermore been a symbol for the Cross (thanks to the manner of martyrdom of Saint Andrew), it may be suggested that referring to "Xmas" places the Christmas narrative within the greater, complete narrative of the life and mission of the Messiah, the Sacrifice, the Passover Lamb. It whispers resurrection in the midst of happy shouts of the announcement of a new birth.
If some outside our group are victoriously gloating that they have eradicated all religious sentiment from the holiday by blotting out the name of Christ from the word "Christmas," they may quite miss the point. They set a philosophical trap for themselves because it was our word first, and they boldly (and accidentally) proclaim our story for us. We should be proclaiming it, too.
To put it succinctly, "Xmas" is a richly Christian construct, one we should not be resentful of, but rather claim, celebrate, and shout with great joy and gratitude at the arrival of our salvation, our X arrived for us (therefore let us keep the feast).