“Christmas,” the word, comes from the Old English Crīstesmæsse, or literally, “Christ’s Mass” and is festival commemorating the birth of Jesus Christ, now observed on December 25. It closes the period of Advent and begins the 12 days of Christmastide, which end after twelfth night.
The first recorded date of Christmas being celebrated on December 25th was in 336AD, during the time of the Roman emperor Constantine, the first Christian emperor. A few years later, Pope Julius I officially declared that the birth of Jesus would be celebrated on the 25th of December.
Actually, Christ was probably born in the fall of the year. It has been mistakenly believed He was born around the beginning of winter, but according to the Adam Clarke Commentary, it was the Jewish custom to send out their sheep to the deserts at the time of Passover in early spring and bring them home when the first rains began, in in early-to-mid fall. Shepherds watched over them during this time. Since the shepherds had not yet brought their flocks home at the time of Christ’s birth, the event had to have happened sometime in late September. From Luke 2:8: “And there were in the same country shepherds abiding in the field, keeping watch over their flock by night.”
So how did Christ’s birth come to be celebrated on December 25? This date was chosen because it roughly coincided with various Roman festivals. First there was the idolatrous festival of Saturnalia, a time of merrymaking and exchanging of gifts in early Rome. This occurred each year around the beginning of winter, or the winter solstice, when the sun takes its lowest path across the sky and the 
days begin to lengthen, assuring another season of growth. Saturnalia, of course, celebrated Saturn—the fire god, and also the god of sowing. Saturn was worshipped in this dead-of-winter festival so he would come back to warm the earth for spring planting. Some of the trappings of the Saturnalia parallel what so many of us do today to celebrate Christmas: decorating homes with greenery, giving gifts, singing songs, and eating special foods.
Some Romans worshiped the god Mithra, first found in the Indian Vedic religion as 
Mitra, 3500 years before the birth of Christ. Interestingly, the Indian Mirta is also a solar deity, being the light and power behind the sun. Mithra was believed to come from a virgin birth, like Christ, and thought by many to have been born on December 25. However, there is no evidence to support this.
In fact, December 25 was considered the birth date of Sol Invictus, literally the “unconquered sun.” Sol Invictus was the official sun god of the later Roman Empire and a patron of soldiers. In 274, the emperor Aurelian made the cult of Sol Invictus one of the traditional Roman cults.
For the past two hundred years, it has been generally thought December 25 was chosen for Christmas in order to correspond with the Roman festivals of Saturnalia, Sol Invictus or the birth of Mithra, in order to convince Rome’s pagan citizens to accept Christianity as the empire’s official religion and to promote the church’s identification of God’s son with the celestial sun.
Very much enjoyed this posting, Noelle.
Thank You
big hugs
john
Glad you liked it – I like doing research!
By the end of the 3rd century, Christmas in Rome was celebrated on December 25, which coincided with a major pagan feast. The Eastern churches, meanwhile, continued to observe Christmas on January 6. The Armenian Church has maintained that ancient tradition to this day, whereas the Greek-speaking Christian world switched to the Latin tradition at the end of the 4th century.
I think that has to do with the difference between the Julian and Gregorian calendars which is 9 or so days.
Very interesting! I knew bits and pieces but was missing a lot of this information. It’s nice to see it laid out in a readable format!
I knew some of this, but not quite so much as you’ve provided above. Very interesting. Stuff like this always fascinates me.
Great stuff, thanks – and to Mihrank too, for explaining why the Eastern churches stick with what we call Epiphany, the day the Kings arrive and the 12th Day of Christmas. I dont think that’s a coincidence is it?
I think it also has to do with the differences between the Julian and Gregorian calendars and which calendar the religions observe. The difference is about 9 days as I recall.
That’s informative, thank you x
https://latinaindubai.wordpress.com
Love, love, love your historical posts. This is a great one! Sharing! 🙂
Thank you Alex! Depending on my cookie baking, I might have another one in me before the Big Day!