Christmas as such was probably not celebrated in the first couple of centuries after Jesus' birth at all. Far more interesting to the first Christians was Easter, their version of Passover, which commemorated the last climactic events of Jesus' ministry rather than the poignant stories of his beginning. Since Jesus' last great conflict with the Roman authorities and their collaborators had taken place at Passover, his death was interpreted along lines suggested by the great Jewish festival, and his resurrection celebrated in conjunction with it.
The observance of Christmas as a major feast appears only rather later, in the fourth century or at the end of the third. By this time Christians were placing greater emphasis on God's personal presence in a human being throughout Jesus' life - the "incarnation" or enfleshment of God, as teachers such as Irenaeus of Lyons and Athanasius of Alexandria put it. Jesus' own conception and birth thus became matters of greater concern and curiosity in popular belief and ritual as well. Christians had also come gradually to observe a greater variety of holidays, such as those commemorating the deaths of martyrs; these anniversaries of heroes who died for their faith were known as "birthdays," the occasion of a new birth to life in God's presence. The celebration of Jesus’ literal birthday was not such a huge leap.
Yet the appearance of a specific date for Christmas is somewhat mysterious. In fact there were originally two, December 25th and January 6th (now known as the Feast of the Epiphany), which came to be observed in the West and East of the
Roman Empire respectively. Both these dates were close to the winter solstice - December 21st in our modified Gregorian calendar. Mid-winter festivals had already been common - the Romans had their Saturnalia, and other peoples of northern and western Europe kept holidays at similar times.
Ancient authors had already noticed the connection, but nineteenth-century scholars, spurred on by the emergent study of comparative religion, seized upon this coincidence with something approaching fervor. Since these dates could not really be linked to the birth date of the historical Jesus, were they not just thinly-veiled pagan festivals, appropriated and Christianized only superficially? It was no secret that Christian leaders such as Pope Gregory the Great had encouraged the "baptism" of pagan religious observances for evangelistic purposes, and this connection could not have been ignored or avoided in the expansion of Christmas feast.
Such views have become dogma in many popular discussions, but the truth seems likely to be more complex. There are two key problems with to the "solstice" theory. The first is that the oldest evidence for Christmas festivals is just slightly too early to make sense as a Christianized Saturnalia, since it comes from the time when Christians were still a persecuted group distinguished by refusal to adopt obvious pagan customs, rather than by readiness to adapt. The second is that while feasts of the incarnation were indeed late in achieving recognition and widespread liturgical celebration, these actual dates – or one of them at least - had been identified much earlier. Clement of
, who wrote around 200 CE, was already aware of the January 6th date given for Jesus' birth. Alexandria
The key to understanding the emergence of both January 6th and December 25th as dates for Jesus’ birth festival lies – strange as it may seem - in the dating of Passover and of Jesus’ death, which were known to have coincided. Christians in the eastern provinces of the
Roman Empire took the fourteenth day of the first Spring month (‘Artemisios’) in the local calendar - April 6th to us – as their equivalent for the date of Passover, Nisan 14th. In the West however, speculation about the date of Jesus’ death had landed on a different date, March 25th, by about the year 200.
These two Paschal dates are of course nine months before the eastern and western feasts of the incarnation, January 6th and December 25th. So some Second-century Christians had apparently calculated the birth of Jesus on the basis that his death and conception took place on the same day – and come up with two close, but different, results.
Aside from the complicated calculations, the connection between Jesus' conception and death seems odd. Yet Jewish writings of the same period reflect a similar belief that the great events had taken place on the same dates: the Talmud records the view that the world was created, the Patriarchs born, and the world would be redeemed, all in the month of Nisan. Thus the dates of Christmas and Epiphany may well have begun not with opportunistic borrowings of pagan observances, but from Christian theological reflection on history; Jesus would have been conceived – become incarnate – at the same time he was to die, and born nine months later.
The commonly-drawn connection with the winter solstice is not irrelevant. Clearly this coincidence made the expansion of the feast of the nativity more strategically important, and Christians were not backward in appropriating some of the symbols already known to pagans. Yet the origin of the date of Christmas is probably owed more directly to Judaism than to paganism, and the growth in the importance of the feast is more directly connected with deepening reflection by Christians of the early centuries on the significance of the event it commemorated.
Based on some work of mine that appeared in Bible Review some years ago. The original scholarship however comes from Louis Duchesne and Thomas Talley, whose work I gratefully acknowledge.