When I was a child I was told that to write X-mas instead of Chistmas was bad. X-mas was, the teachers said, an unbelievers way of having "Christmas" but leaving Christ out.
My children, thirty years later, carry home the same woeful tale.
Guess what! It isn't true! For one thing the X in X-mas isn't really an X. It is the Greek letter chi(ki), transliterated as kh and representing the Greek word Khristos, which is Christ, of course.
So X-mas is really Christmas too. If you don't believe me look up X-mas in the dictionary. Uh, unfortunately, you have to look it up under the letter X.
Speaking of Greek, do you know what IXTHUS means? It is the Greek word for fish. So what!? Well now for the first time you may understand why a fish is a well-known symbol of Christianity. Here is why: the first letter of the Greek word for fish is the first letter of the Greek word for Jesus, (I) lesus. The second letter X, stands for the word Xristos (Christ). The two letter TH stand for THEOS (GOD). The U stands for the Greek word for Son (Uios). The final letter S stands for the Greek word Savior (soterios).
Put it all together and the letters of the word give this message:
I - Jesus X - Christ TH - god's U - Son S - Savior
So IXTHUS (FISH) = a symbol of Christianity,