Date of celebration

For many centuries, Christian writers accepted that Christmas was the actual date on which Jesus was born. In the early eighteenth century, scholars began proposing alternative explanations. Isaac Newton argued that the date of Christmas was selected to correspond with the winter solstice, which the Romans called bruma and celebrated on December 25. In 1743, German Protestant Paul Ernst Jablonski argued Christmas was placed on December 25 to correspond with the Roman solar holiday Dies Natalis Solis Invicti and was therefore a "paganization" that debased the true church. According to Judeo-Christian tradition, creation as described in the Genesis creation myth occurred on the date of the spring equinox, i.e. March 25 on the Roman calendar. This date is now celebrated as Annunciation and as the anniversary of Incarnation. In 1889, Louis Duchesne suggested that the date of Christmas was calculated as nine months after Annunciation, the traditional date of the conception of Jesus.

The December 25 date may have been selected by the church in Rome in the early fourth century. At this time, a church calendar was created and other holidays were also placed on solar dates: "It is cosmic symbolism...which inspired the Church leadership in Rome to elect the winter solstice, December 25, as the birthday of Christ, and the summer solstice as that of John the Baptist, supplemented by the equinoxes as their respective dates of conception. While they were aware that pagans called this day the 'birthday' of Sol Invictus, this did not concern them and it did not play any role in their choice of date for Christmas," according to modern scholar S.E. Hijmans.