True
Well there is no actual documentary evidence for that view, and it doesn't conform exactly to the dates of the traditional Roman Saturnalia which started earlier. It's possible, although it can only ever be speculative. It certainly isn't the 'fact' that many people seem to assume.
Exact dates are not necessary. It is generally accepted all over Europe and in Rome the celebrations were a week or longer centering on the Winter Solstice.
Also the 25th date was likely being observed by groups like the Donatists when Rome was still persecuting Christians.
In about 400 C.E., Augustine of Hippo mentions a local dissident Christian group, the Donatists, who apparently kept Christmas festivals on December 25, but refused to celebrate the Epiphany on January 6, regarding it as an innovation. Since the Donatist group only emerged during the persecution under Diocletian in 312 C.E. and then remained stubbornly attached to the practices of that moment in time, they seem to represent an older North African Christian tradition.
Vague unsubstantiated reference.
Better reference: From:
How December 25 Became Christmas - Biblical Archaeology Society
Jesus’ ministry, miracles, Passion and Resurrection were often of most interest to first- and early-second-century C.E. Christian writers. But over time, Jesus’ origins would become of increasing concern. We can begin to see this shift already in the New Testament. The earliest writings—Paul and Mark—make no mention of Jesus’ birth. The Gospels of Matthew and Luke provide well-known but quite different accounts of the event—although neither specifies a date. In the second century C.E., further details of Jesus’ birth and
childhood are related in apocryphal writings such as the
Infancy Gospel of Thomas and the Proto-Gospel of James.
b These texts provide everything from the names of Jesus’ grandparents to the details of his education—but not the date of his birth.
Finally, in about 200 C.E., a Christian teacher in Egypt makes reference to the date Jesus was born. According to Clement of Alexandria, several different days had been proposed by various Christian groups. Surprising as it may seem, Clement doesn’t mention December 25 at all. Clement writes: “There are those who have determined not only the year of our Lord’s birth, but also the day; and they say that it took place in the 28th year of Augustus, and in the 25th day of [the Egyptian month] Pachon [May 20 in our calendar] … And treating of His Passion, with very great accuracy, some say that it took place in the 16th year of Tiberius, on the 25th of Phamenoth [March 21]; and others on the 25th of Pharmuthi [April 21] and others say that on the 19th of Pharmuthi [April 15] the Savior suffered. Further, others say that He was born on the 24th or 25th of Pharmuthi [April 20 or 21].”2
Clearly there was great uncertainty, but also a considerable amount of interest, in
dating Jesus’ birth in the late second century. By the fourth century, however, we find references to two dates that were widely recognized—and now also celebrated—as Jesus’ birthday: December 25 in the western Roman Empire and January 6 in the East (especially in Egypt and Asia Minor). The modern Armenian church continues to celebrate Christmas on January 6; for most Christians, however, December 25 would prevail, while January 6 eventually came to be known as the Feast of the Epiphany, commemorating
the arrival of the magi in Bethlehem. The period between became the holiday season later known as the 12 days of Christmas.
The earliest mention of December 25 as Jesus’ birthday comes from a mid-fourth-century Roman almanac that lists the death dates of various Christian bishops and martyrs. The first date listed, December 25, is marked:
natus Christus in Betleem Judeae: “Christ was born in Bethlehem of Judea.”
3 In about 400 C.E., Augustine of Hippo mentions a local dissident Christian group, the Donatists, who apparently kept Christmas festivals on December 25, but refused to celebrate the Epiphany on January 6, regarding it as an innovation. Since the Donatist group only emerged during the persecution under Diocletian in 312 C.E. and then remained stubbornly attached to the practices of that moment in time, they seem to represent an older North African Christian tradition.
In the East, January 6 was at first not associated with the magi alone, but with the Christmas story as a whole.
So, almost 300 years after Jesus was born, we finally find people observing his birth in mid-winter. But how had they settled on the dates December 25 and January 6?
There are two theories today: one extremely popular, the other less often heard outside scholarly circles (though far more ancient).
4
The most loudly touted theory about the origins of the Christmas date(s) is that it was borrowed from pagan celebrations. The Romans had their mid-winter Saturnalia festival in late December; barbarian peoples of northern and western Europe kept holidays at similar times. To top it off, in 274 C.E., the Roman emperor Aurelian established a feast of the birth of
Sol Invictus(the Unconquered Sun), on December 25. Christmas, the argument goes, is really a spin-off from these pagan solar festivals. According to this theory, early Christians deliberately chose these dates to encourage the spread of Christmas and Christianity throughout the Roman world: If Christmas looked like a pagan holiday, more pagans would be open to both the holiday and the God whose birth it celebrated.
Despite its popularity today, this theory of Christmas’s origins has its problems. It is not found in any ancient Christian writings, for one thing. Christian authors of the time do note a connection between the solstice and Jesus’ birth: The church father Ambrose (c. 339–397), for example, described Christ as the true sun, who outshone the fallen gods of the old order. But early Christian writers never hint at any recent calendrical engineering; they clearly don’t think the date was chosen by the church. Rather they see the coincidence as a providential sign, as natural proof that God had selected Jesus over the false pagan gods.
It’s not until the 12th century that we find the first suggestion that Jesus’ birth celebration was deliberately set at the time of pagan feasts. A marginal note on a manuscript of the writings of the Syriac biblical commentator Dionysius bar-Salibi states that in ancient times the Christmas holiday was actually shifted from January 6 to December 25 so that it fell on the same date as the pagan Sol Invictus holiday.
5 In the 18th and 19th centuries, Bible scholars spurred on by the new study of comparative religions latched on to this idea.
6 They claimed that because the early Christians didn’t know when Jesus was born, they simply assimilated the pagan solstice festival for their own purposes, claiming it as the time of the Messiah’s birth and celebrating it accordingly.
More recent studies have shown that many of the holiday’s modern trappings do reflect pagan customs borrowed much later, as Christianity expanded into northern and western Europe. The Christmas tree, for example, has been linked with late medieval druidic practices. This has only encouraged modern audiences to assume that the date, too, must be pagan.
There are problems with this popular theory, however, as many scholars recognize. Most significantly, the first mention of a date for Christmas (c. 200) and the earliest celebrations that we know about (c. 250–300) come in a period when Christians were not borrowing heavily from pagan traditions of such an obvious character.
Granted, Christian belief and practice were not formed in isolation. Many early elements of Christian worship—including eucharistic meals, meals honoring martyrs and much early Christian funerary art—would have been quite comprehensible to pagan observers. Yet, in the first few centuries C.E., the persecuted Christian minority was greatly concerned with distancing itself from the larger, public pagan religious observances, such as sacrifices, games and holidays. This was still true as late as the violent persecutions of the Christians conducted by the Roman emperor Diocletian between 303 and 312 C.E.
This would change only after Constantine converted to Christianity. From the mid-fourth century on, we do find Christians deliberately adapting and Christianizing pagan festivals. A famous proponent of this practice was Pope Gregory the Great, who, in a letter written in 601 C.E. to a Christian missionary in Britain, recommended that local pagan temples not be destroyed but be converted into churches, and that pagan festivals be celebrated as feasts of Christian martyrs. At this late point, Christmas may well have acquired some pagan trappings. But we don’t have evidence of Christians adopting pagan festivals in the third century, at which point dates for Christmas were established. Thus, it seems unlikely that the date was simply selected to correspond with pagan solar festivals.
The December 25 feast seems to have existed before 312—before Constantine and his conversion, at least. As we have seen, the Donatist Christians in North Africa seem to have known it from before that time. Furthermore, in the mid- to late fourth century, church leaders in the eastern Empire concerned themselves not with introducing a celebration of Jesus’ birthday, but with the addition of the December date to their traditional celebration on January 6