One widespread explanation of the origin of this date is that December 25 was the Christianizing of the dies solis invicti nati (“day of the birth of the unconquered sun”), a popular holiday in the Roman Empire that celebrated the winter solstice as a symbol of the resurgence of the sun, the casting away of winter and the heralding of the rebirth of spring and summer. Indeed, after December 25 had become widely accepted as the date of Jesus’ birth, Christian writers frequently made the connection between the rebirth of the sun and the birth of the Son
