Most of us have wondered at one time or another why Christmass, the birth of Jesus Christ, is celebrated on December 25th. There is no verse in any of the Gospels, or anywhere else in the Bible for that matter, that says, “Mary and Joseph checked into the inn on December 25th, but all they could get was the stable because all of the regular rooms were taken.” It simply is not there. The Bible gives us no clear cut, simple date for the birth of Christ.
The birth event itself apparently was not celebrated in the very early Christian Church; what mattered were the Crucifixion and the Resurrection, the Easter events. These were celebrated from the very beginning, but Christ’s birth was not cause for particular notice at first. It is not until about the fourth century that a date for the birth of Christ begins to be established with any degree of agreed certainty. The question we are interested in here is, how would such a date be established, especially so long after the fact?
Many are familiar with the idea that the Christian Church simply co-opted existing pagan festivals, “baptizing” them, if you will, to turn them into Christian festivals. This idea has been suggested in regard to Christmass, namely that it is the Christianized version of the pagan feast of Sol Invictus, the victorious sun god coming back from defeat at the winter solstice. This idea has been widely taught for a number of years.
There is another idea that has come to light recently that explains the choice for December 25th. It was, apparently, commonly understood that people would die on the same date as the date on which they were conceived. This sounds strange to modern people who are accustomed to having death come from so many different sources, but try to put yourself in the place of simple people for whom death almost always came by either old age or by an accident, unless one got crossways with the authorities. It is not too hard to imagine how they might hold such a belief as this.
Jesus died on the 14th day of Nisan of the Hebrew calendar, which translates to the 25th of March on the Roman calendar, the day that we now know as the Annunciation, the day that Mary was told by the Archangel that she would bear the Saviour. Nine months forward from that date brings us to December 25th, the date for Christmass.
In the Christian East, the calculation was done a bit differently, starting with the 14th day of Nisan and working through the 14th day of the first spring month, Artemisios, in the local Greek calendar, they came out with what we would understand to be April 6. This leads them to put Christmass on January 6th, Epiphany.
This does not prove that this was the reasoning behind the choice of December 25th for Christmass, but it seems to add some interesting insights into the likely process.
All of the above is condensed from a longer article “How December 25 Became Christmas” by Andrew McGowan at http://www.bib-arch.org/e-features/christmas.asp#location1