Many people take offense when the holiday on 25 December is referred to as Xmas, believing it ignores Jesus, whose birth it celebrates. Not so much.
One of the major hubs of early Christianity was Greece. The New Testament tells us that both St. Paul and St. Andrew (among others) preached in Greece. St. Andrew was crucified there, with his cross being in the shape of an “X”. Today, that shape is still referred to as Andrew’s Cross, such as in the flag of Great Britain.
The X is significant for a more important reason. The Greek word “Christos,” begins with the letter chi (pronounced “key”) followed by the letter rho. Perhaps you’ve seen the Chi Rho in a church or other religious site.
Early Christians, when persecution began, would identify themselves to one another by doodling Christian symbols in the dirt with their walking sticks. To others, it was meaningless. It is believed among the symbols that Christians would recognize included a simple fish and the Chi Rho.
So, Merry Christo-mas!