Christmas is a season not a day.
In spite of what most people seem to think, the time before Christmas is not the Christmas season. On Christmas Day, the season is actually just beginning.
In the culture at large, the weeks before Christmas are a time for celebration, with lots of excitement from the Christmas music, lights, decorations, and parties.
In the Church, the four weeks before Christmas are a time of preparation for the celebration of Christ's birth, a time of sober waiting. These four weeks of waiting start on the first Sunday of December and are called Advent, which means "coming." Advent is so important to the Church that it is the start of the liturgical year. During Advent, we anticipate the celebration of the First Coming of Christ that starts on Christmas Day and also are reminded to be ready for Christ's expected Second Coming at the end of the world. The Advent vestments are purple, the color of penance. The Christmas vestments are gold or white, to show our joy.
It seems to me that in the real spirit of the season, Christians should only start the singing of Christmas hymns and carols on Christmas Day, and hold off on the decorations and the parties until then. The festivities can then continue throughout the Twelve Days of Christmas up to the Feast of the Epiphany. Or even longer.
The Twelve Days of Christmas end January 5. The Epiphany, which is also called the Feast of the Wise Men, is celebrated on January 6. At my house, the wise men finally arrive at my manger scene on January 6 after they have been wandering around the living room ever since the creche was put up.
But Christmas is not over even at Epiphany.
In the Catholic liturgical year, the Christmas season ends forty days after it starts, on February 2, on a feast day that has been called many names because it celebrates many things. The feast has been called Candlemas because candles are blessed at the Masses that day. The Purification of Our Lady in the Temple is a second name. In the Jewish religion, a woman presented herself for purification at the temple forty days after the birth of a male child. The Presentation of the Child Jesus is the current title of the feast. When Christ was carried into the Temple forty days after His birth to be dedicated to God as required by Jewish Law for every firstborn son, He was recognized by an old man named Simeon and by an old woman named Anna, who had been waiting years for His coming. In some traditions, the feast is also called The Meeting because of Christ's meeting with the prophet Simon and the prophetess Anna.
These remarks just skim the surface of all the rich symbolism and significance of these feasts. And there are several more feasts during this time that I can't go into now.
The point to remember is that the Catholic Church dedicates a long time, the symbolically important number of forty days, to the celebration of Christmas, and, contrary to public opinion, the celebration does not end on December 25 but starts on that day.