We have a Christmas tree in the back of our sanctuary at church that is full of Chrismons. The word "Chrismon" is a derivative of two words (ChHRISt+MONOgram). By the way, the Chrismons at our church, like many others, are handmade because according to all I've read, they cannot be made for profit, hence you won't find them in your neighborhood store that sells Christmas decorations.
Technically, if the ornaments on a Christmas tree are comprised mostly of Christian symbols, the tree is known as a "Chrismon Tree." Most Chrismons are white with gold decorations of beads, ribbon, glitter, etc.
Chrismons are symbols that stand for Christ. The symbol reminds us of some aspect of Christ's life. The symbol points us, our minds toward Christ. There are many,many Chrismons and I have posted one here for you that is explained. But you can do some research on your own and find all the different symbols. It is very fascinating.
If you look carefully on the tree you will see some Chrismons that are "X's" or a combination of an "X" and what looks like a "p." Those are not English letters, but Greek letters. The letter that looks like the letter "p" in our alphabet is really the Greek letter "Rho" which is equal to our letter "R." The "X" is the Greek letter "Chi" and is equal to a "CH" in English letters. The "Chi," the Greek letter that looks like our "X" is a symbol of Christ. It is the first two letters of the word "Christ." When combined with the "Rho," the Greek letter that looks like our letter "p," the symbol then stands for the first THREE letters, "Chr" of the word Christ.
So, when people, like me, go on and on about 'X-mas' leaving out Christ, they don't know what they're talking about. So, now that YOU know, you can enlighten them.