OK, I grew up under the assumption that spelling Christmas as "Xmas" was a way of naming the holiday separate from its religious beginnings. I always kinda hated it, thinking that people were so averse to religion that they were x-ing out Christ's name. (Some kind of politically-correct thing like trying to change women to womyn.)
Plus, I figured it was catching on because it saved space when printing up signs :)
I was just dumb and wrong, and since I've heard others voice similar opinions, I thought I'd help to set the record straight: The X in Xmas is actually the greek letter Chi, which was a common abbreviation of Kristos, Christ's name. (Using the roman alphabet, I've also seen it written Xpistos. In greek, I believe that would be Χριστος.)
It is interesting to note, however, that my American Heritage English Dictionary does have the following Usage Note:
The abbreviation Xmas has been used for hundreds of years. In modern use it is considered informal and appropriate only in such commercial contexts as advertisements and signs.
Other authoritative-looking sources backing me up:
| created 2001-Jan-3 | page modified 2001-Jan-3 |