ANSWER: Abbreviating the word Christmas to Xmas does not 'cut Jesus short' as your Emailed question suggested. Before we explain this, let us first discover where the "X" in the abbreviation came from and then we will go back fifty years or so when the idea to shorten the name of the holiday seems to have first caught on.
The word for Christ in the Greek is Christos (which is Strong's Exhaustive Concordance #5547). In Greek, the twenty-second letter of their alphabet is written as "X" and is pronounced CHI. It is the first Greek letter in the word for Christ. Many years ago, retailers realized they could save both space and ad costs by shortening the word Christmas to Xmas using the letter X to replace the letters "Christ." After a few years of this practice, however, the religious community countered with the slogan that called for Christ's name to be put BACK into the holiday. Generally, they succeeded, especially since advertising layouts no longer depended on the number of letters in a word.
Changing the Christmas holiday's name to Xmas does not disrepect the Lord. This is primary because most people (whether they go to church or not) realize Christ never really was in the holiday in the first place. Most know that its origin is based on pagan, not Christian, beliefs and practices. For example, the celebration uses pagan sex symbols (orbs placed on the tree) to commemorate our Savior's birth.
These facts about the most popular holiday in the world should be no surprise to most people, since every year we are reminded by the media and even ministers and pastors that Jesus was not born anywhere near December 25. In fact, a good argument can be made that he was born in the FALL of the year, around our September - October period, in 5 B.C. The date of December 25 was picked by the Catholic Church many years ago because it was when the pagans had an important festival. The thinking was that if the church adopted some pagan holidays and stripped off some of the more blatant non-Christian activities ("Christianizing" it in a sense) it would be in a better position to attract the pagans and have them convert. Think of this as a membership-building program, where the goal is to build the church's membership (and, ultimately, its power and bank account).
A non-Christian celebration that was used to worship the Sun was adopted, changed, and had its focus changed from worshipping the Sun to worshipping the Son. Its celebration was eventually called the mass of Christ or CHRISTMAS.
Getting back to the idea of ancient sex symbols used to honor Christ at Xmas. The pretty balls you might use to decorate your tree originated with the pagans as a representation of the female egg. Candles that are sometimes used around Christmas were at one time used by pagans (non-Christians) as a symbol for an erect penis (the pagans loved to worship their ability to procreate).
The wreath many people even today still hang on their door was first used, again, by those worshipping a false god, to symbolize the opening of a female's vagina. In addition, although it is not seen so frequently today, years ago wreaths use to have a candle standing upright within them. It does not much of an imagination to see what they together symbolize. Even something like mistletoe, used today to solicit a kiss, had it start with the Druids.
God has clearly stated what he thinks about mixing how he wants to be worshipped with the practices and symbols used by those who worship false or pagan gods.
". . . take heed to yourself that you are not ensnared to follow them . . . and that you do not inquire after THEIR gods, saying, 'How did these nations serve THEIR (false) gods? I also will do likewise.' You shall NOT worship the LORD your God in that way" (Deuteronomy 12:30 - 32)
Why do churches today continue to combine pagan festivities and practices to their observance of the day they have selected to remember Christ's birth? It is simply because of tradition. However, Jesus told the religious leaders of his day that following man's traditions regarding how to obey and worship God is simply not acceptable (Mark 7:9). Since neither God the Father or Jesus ever endorsed Christmas in the first place, and therefore were never "in" it, shortening it to XMAS does not disrespect our Savior.