why is the abbreviation for christmas xmas

The abbreviation "Xmas" is actually a very old way of writing the word "Christmas." It comes from the Greek word "Xristos," which means "Christ." Over time, the "X" in "Xristos" became a symbol for the cross, which is used in the Christian faith to represent the crucifixion and resurrection of Jesus Christ. So when people started to use the abbreviation "Xmas" for "Christmas," they were actually using a symbol for the Christian faith.