Max9
X has been used as a scholarly abbreviation for Christ since antiquity. The Roman alphabet X derives from the Greek letter Chi, which was the first letter in "Christos," meaning "anointed."
I once tried to explain that to an American woman who was claiming that "Xmas" was an attempt by "certain people to remove Christ from Christmas." Her response to my etymology was that we shouldn't use Greek words for Jesus because "the Bible was written in English."
Deadass. I had to walk away to keep from laughing.