Christmas Questions
Questions and answers from the New York Public Library Reference Desk

Why is the word "Christmas" abbreviated as "Xmas"?
Because the Greek letter "x" is the first letter of the Greek word for Christ, "Xristos." The word "Xmas," meaning "Christ's Mass," was commonly used in Europe by the 16th century. It was not an attempt to take "Christ" out of "Christmas."

What is the earliest reference to Christmas's being celebrated on December 25?
In the middle of the 2nd century, Christians in Antioch were already celebrating Christ's birth on that day. The day was not officially recognized by the Church as the date of Christ's birth until A.D. 350.

Why December 25?
The day was formerly celebrated by worshippers of the god Mithra as the Day of the Invincible Sun. It seemed natural to Christians to replace Mithra with Christ—called in the Bible the Sun of Righteousness.

What do they observe in China on December 25?
In the Republic of China—Taiwan—they observe Constitution Day, a national holiday.

When did trees become part of Christmas celebrations?
Evergreen trees and wreaths have been used as symbols of eternal life since the ancient times of the Egyptians, Chinese, and Hebrews. After the coming of Christianity, evergreens were still used in Scandinavia—to scare away the devil. In the Middle Ages, the  Christmas tree, decorated with candles and wafers (symbols of Christ and the Host), became popular, as did the gaily decorated wooden Christmas pyramid. By the 16th century, the two objects merged into what we now know as the Christmas tree. By the 19th century, the Christmas tree was popular across Europe and the United States.