How did the word Christ come to be replaced by the letter “X”? Turns out it goes back to the very beginnings of Christianity.
“Using the symbol ‘X’ for Christ is a tradition that dates far back into the history of Christianity into the first few centuries. That’s because our letter ‘X’ is identical to the Greek letter ‘chi’, which is the first letter for Christos in Greek, and so early Christians many times would see the letter ‘X’ or combine that with the letter ‘rho’ in Greek to symbolize Christ,” said Father Robert Busch, PhD, Amarillo Diocese Schools Director.
Xmas therefore means “Christ’s Mass,” so in many ways, the “X” in Xmas stands for Christ. But people unaware of the Greek origin of this “X” often mistakenly interpret Xmas as an informal shortening pronounced (eks-mas). Many therefore frown upon the term Xmas because it seems to them a commercial convenience that omits Christ from Christmas. It’s also important to note that it is a written abbreviation, and should not be pronounced ‘X’mas, but instead as “Christmas”.
Another interesting fact, in olden times when paper and ink were precious commodities, the “X” was used to save space when printing.