‘Tis the season when some Christians take umbrage at Xmas. Not at the holiday; at the spelling.
Some think that using “X” instead of writing “Christ” is either a liberal or commercial attempt to demean the name of the holiday or to make the word easier to fit into ads. ‘Tis a reasonable assessment from their point of view.
Christians themselves are responsible for Xmas. They created the abbreviation and have used an abbreviation of the Greek for at least 1,000 years. Χριστος was ancient Greek for “Christ.” Eventually, that was shortened to u2627 (CHI RHO). By at least the 1480s, it had become X.