Perhaps the sight of this nifty, festive abbreviation makes you want to get your red marker pen out. Alternatively, you might be suspicious that its an attempt to secularise Christmas (similar to sometimes unpopular modern greetings such as happy holidays). However, the use of this little x goes back much further than a millennial attempt to make Christmas sleeker and secular.
Sources tell us that the first appearance of the word Xmas dates back to the 11th century, if you consider XPmas to be a variant of the modern Xmas. Anglo-Saxon scribes needed to save space when using expensive parchment and XP was a convenient abbreviation for Christ. Why? Because in Greek, Chi and Rho are the first two letters of ???????. Even if thats all Greek to you, Im sure you have guessed, the translation is Christos, or Christ. The XP (Chi-Rho) sign was also emblazoned on military banners by Christian Roman emperor Constantine I for use in war.
So, that is arguably the early etymology of Xmas. Usage of the word with the spelling as we know it today can be traced back to the 18th century. It is found in various books and letters, including works by Lord Byron, Samuel Coleridge and even childrens author Lewis Carroll. It was included in the American Royal Standard English Dictionary in 1800, where it was listed as an abbreviation for Christmas. Use of Xmas from the 19th century onwards has echoed the 11th century scholars need for concision, having predominately been used in marketing contexts and on greeting cards, where space is often limited. This is perhaps where the discomfort of some Christians stems from; the association of this word with marketing and commodification.
However, when youre ringing in the Yuletide and decking the halls with boughs of holly, you can rest assured that Xmas is a very ancient and distinguished word indeed, and there is etymologically more Christ in it than people may realise!