Why do we call Christmas Christmas?

Answer 1

"Christ" + "mass" = "Christmas."

Christian churches have a Mass on the 25th of December (the date designated a long time ago as the date of the birth of Jesus) to remember that Jesus Christ was born - so Christ + mass = Christmas

Other feast days also have the word ~mas as a suffix, but their use is dying out - Michaelmas is the day that Mass was dedicated to Saint Michael, and Candlemas, a day when candles were blessed.

Answer 2

At the time the Roman emperor Constantine became a Christian and wished to convert the Roman Empire to Christianity, it was necessary to change the existing winter holiday in honor of the god Saturn, which was called the Saturnalia, into a Christian holiday, so Christmas was invented for that purpose.

Answer 3

It is called this because it is a mix between Christ and Mass. One being Jesus, the other being a catholic service. I hope this answers your question.