For most of my life I, along with many others, was offended by the term “Xmas”. It seemed obvious that people were scratching out the name of Christ and that notion bothered me. It was just a few years ago when a fellow Christian told me about the historic Christian origins of this term. I had to say I was kind of blown away and also a little embarrassed that I was completely ignorant of this before. So here are 5 fast facts about the term “Xmas”…
As one can see by looking at these first two letters they look like an English X and P and so X or sometimes XP became a well-known Christian symbol. This symbol is called the labarum or Chi-Rho. The Chi-Rho symbol seems to be similar in its usage to the well-known “Christian Fish”. The fish symbol has been used since the early times of the church because the Greek acronym “Icthus” (Jesus Christ Son of God Saviour) happens to spell “fish”.
R.C. Sproul http://www.ligonier.org/blog/why-is-x-used-when-it-replaces-christ-in-christmas/
Dennis Bratcher http://www.crivoice.org/symbols/xmasorigin.html