Is it Offensive to Write Christmas as X-mas?

How did our flippant habit of referring to Christmas as Xmas ever get started?

—J.C., Ocala, Fla.

Many people are offended by the abbreviation and assume it’s a modern abomination. But, in fact, it’s at least 1,000 years old and was not meant to be disrespectful or used that way. What appears to be an X in our modern Roman alphabet is actually the Greek letter chi, the first letter of the word Christos, meaning Christ. Two possibilities for the shortening: Use of the name of Christ in another word may have looked unseemly, or it may have been done for a religious reason. Either would mean that we now see the abbreviation as the opposite of what was intended.