What is the origin of Christmas?

The feast of Christmas was not celebrated in any way in the early days of Christianity. In a religious branch born of Judaism, there was no reason to celebrate the birth of the Messiah, who only became such in adulthood. Furthermore, the end of the world was seen as something immediate. If the end of the world is immediate, there is no place for celebrations. The birth of Jesus is only established as a holiday with the passage of time, when Christianity is adopted by the Roman Empire as a legitimate religion. It is at this time that the Church must give religious holidays to the masses. What the church did was take pagan festivals and infuse them with a religious sense. The feast of the Sun was on December 25, the light that conquers the darkness, Christianity could adopt the position of substituting the birth of the undefeated sun for the birth of the Messiah.