Christmas derives its name, "Christ's mass," from the Mass offered in honor of the Birth of Christ. Its early English form was written as "Christes Maesse," and in the course of the change of the English language it eventually became Christmas. In the earliest days of the Church this feast did not exist. Greater stress was placed on the Feast of the Epiphany, because it commemorates the day on which our Saviour was made known to the Gentiles, when the Wise Men came to adore Him. The Feast of the Nativity came gradually into existence in the fourth century. Its first mention is made by the great Christian writer, Clement of Alexandria, about the year 200, and shows that it was celebrated on May 20. About the year 300, the Latin Church began to observe it on December 25, because an ancient tradition assigns that day as the probable date of the Birth of our Saviour.
Love of the Babe of Bethlehem, who was born to redeem us, caused Catholics, in centuries long gone by, to introduce into our churches a representation of the crib, the Divine babe, the Blessed Mother, St. Joseph, and the shepherds. St. Francis of Assisi deserves the credit of making this practice popular. His zeal prompted him to place at Graccio a representation of the cave of Bethlehem. His plan permitted the Faithful vividly to grasp the story of Bethlehem and to realize the poverty and suffering of our Saviour in the bleak, cold stable where He was born. The plan has spread to churches in all parts of the world.
On the Feast of the Epiphany, January 6, it is customary to put the statues of the Wise Men beside the crib. In the early Church, this feast was celebrated with great solemnity because it was the day on which our Saviour was made known to those who were not of Israel. In the fourth century, the Feast of the Nativity came into its own and was given first importance, though in many Catholic countries the custom exists of giving all Christmas presents on the Feast of the Epiphany, since on that day the Wise Men brought gifts to our Saviour.
The Christmas tree is of recent origin. It represents for us the Tree of the Cross. Bethlehem and Calvary are ever associated together in our Christian thoughts, for Christ was born to die on the Tree of Ignominy and thus redeem a sinful world. The lights placed upon the Christmas tree have for us a symbolical meaning. They portray the Light of the World, Jesus Christ.
Our modern Santa Claus, a crude, ridiculous figure, can be traced back to that gentle lover of children - St. Nicholas. This Saint's feast is celebrated on December 6, and parents and friends gave children presents on that day. The Dutch settlers in New York brought this custom with them to the New World, and the giving of presents on December 6 and on Christmas Day became somewhat confused. St. Nicholas was contracted into "Santa Claus" and, with the increasing pagan idea of the Yuletide, became the rollicking, bewhiskered figure so alien to the true Christmas spirit.
Let our children look to the Christ Child for their Christmas presents. There is no need of deception here, and of shattering childish faith. The Christ Child exists; He loves the little ones and He wishes them to love Him. We have no use in a Catholic home for the fraudulent Santa Claus and the pagan Christmas he now symbolizes. Let the Feast of the Nativity of Our Lord Jesus Christ be for young and old a day of spiritual joy and of close union with the Saviour whom we love.
Source: Could You Explain Catholic Practices, Imprimatur 1937