A pseudo-intellectual junk explanation for substituting “X” for “Christ”. Most people who use the term don’t know or care that Christ starts with X in Greek. We speak English here.
SnakeDoc
In 1436 Johannes Gutenberg invented the printing press with moveable type. In the early days of printing typesetting was done by hand and was very tedious and expensive. As a result, abbreviations were common. In religious publications, the church began to use the abbreviation C for the word "Christ" to cut down on the cost of the books and pamphlets. From there, the abbreviation moved into general use in newspapers and other publications, and "Xmas" became an accepted way of printing "Christmas" (along with the abbreviations Xian and Xianity). Even Websters dictionary acknowledges that the abbreviation Xmas was in common use by the middle of the sixteenth century.
Source: http://www.cresourcei.org/symbols/xmasorigin.html
No, it’s not pseudo-intellectual junk. There are still people who read the NT in Greek and the Septuagint OT - which is the version Christ himself quotes on numerous occasions.