25th December every year is celebrated as Christmas to show the reverence for birth anniversary of Jesus Christ. There is no clear evidence on the birth date of Jesus as nothing specific is mentioned in bible. The only information Christian community had was that Jesus was born somewhere during the end of December.
It was decided to celebrate Christmas on 25 December way back in fourth century by church bishops in Rome. In 336AD, Christmas was celebrated for the first time on 25th December during the reign of first Christian Roman Emperor Constantine. After few years,Pope Julius I officially declared that birth of Jesus would be celebrated on 25th December.
Roman Empire decided to celebrate Christmas in end of December as it was already a festive week for them. Festivals such as Winter Solstice and Roman midwinter festivals “Saturnalia” and “Dies Natalis Solis Invicti” were celebrated during third week of December. As it was already a celebration time, they decided to celebrate the birth anniversary of Jesus.
Winter Solstice usually happens on 21-22nd December, is the day when there is shortest time between day and night.For Romans it was the symbolized ending of winter and beginning of spring. This was celebrated to worship sun for winning over the darkness of winter.
Festival of Saturnalia happened between 17th and 23rd December which was celebrated to honor the Roman god Saturn. Another festival “Dies Natalis Solis Invicti” was celebrated as the birthday of Sun.
For Christians Jesus symbolized the light of the world. He was for them the creator of the world.