Why is Christmas Day on the 25th December?

No one knows the real birthday of Jesus! No date is given in the Bible, so why do we celebrate it on the 25th December? The early Christians certainly had many arguments as to when it should be celebrated! Also, the birth of Jesus probably didn’t happen in the year 1 but slightly earlier, somewhere between 2 BCE/BC and 7 BCE/BC, possibly in 4 BCE/BC (there isn’t a 0 – the years go from 1 BC/BCE to 1!).

The first recorded date of Christmas being celebrated on December 25th was in 336, during the time of the Roman Emperor Constantine (he was the first Christian Roman Emperor). A few years later, Pope Julius I officially declared that the birth of Jesus would be celebrated on the 25th December.

However, there are many different traditions and theories as to why Christmas is celebrated on December 25th.

A very early Christian tradition said that the day when Mary was told that she would have a very special baby, Jesus (called the Annunciation) was on March 25th – and it’s still celebrated today on the 25th March. Nine months after the 25th March is the 25th December! March 25th was also the day some early Christians thought the world had been made, and also the day that Jesus died on when he was an adult. The date of March 25th was chosen because people had calculated that was the day on which Jesus died as an adult (the 14th of Nisan in the Jewish calendar) and they thought that Jesus was born and had died on the same day of the year.

Some people also think that December 25th might have also been chosen because the Winter Solstice and the ancient pagan Roman midwinter festivals called ‘Saturnalia’ and ‘Dies Natalis Solis Invicti’ took place in December around this date – so it was a time when people already celebrated things.

The Winter Solstice is the day where there is the shortest time between the sun rising and the sun setting. It happens on December 21st or 22nd. To pagans, this meant that the winter was over and spring was coming and they had a festival to celebrate it and worshipped the sun for winning over the darkness of winter. In Scandinavia and some other parts of northern Europe, the Winter Solstice is known as Yule and is where we get Yule Logs from. In Eastern Europe, the mid-winter festival is called Koleda.

The Roman Festival of Saturnalia took place between December 17th and 23rd and honored the Roman god Saturn. Dies Natalis Solis Invicti means ‘birthday of the unconquered sun’ and was held on December 25th (when the Romans thought the Winter Solstice took place) and was the ‘birthday’ of the Pagan Sun god Mithra. In the pagan religion of Mithraism, the holy day was Sunday and is where get that word from!

(https://www.whychristmas.com/customs/25th.shtml)