Since at least the 5th century, the birth of our Lord Jesus has been celebrated liturgically on the 25th of December. This date makes sense in the cycle of feasts, since it falls nine months after the Feast of the Annunciation (March 25th). It is uncertain which feast came first; the Feast of the Annunciation originated sometime between 376 and 431 (Council of Ephesus), but it is not mentioned in the west until the time of Pope Gelasius (496). The Feast of the Nativity (Christmas) was celebrated from at least the third century and seems to have been fixed on December 25th sometime between 350 and 430.
The historical reasons for the dating of Christ's birth on December 25th are shrouded in mystery; many theories have been put forward. Some, denigrating the Catholic tradition, focus on the fact that the pagan feast of the birth of the sun god Sol Invictus also fell on December 25th. Other theories, relating to the winter solstice or to a Scandinavian pagan holy day, also have their supporters. In many cases, the implication of these theories is that Jesus was not really born on December 25th.
How can we tell when Jesus was born? Is there a way to tell when Jesus' real birthday is? Calculating the birthday of Jesus is not easy, and there really is no level of certainty that we can hope for here. Do we know when Jesus was really born? No. Can we use some data from the New Testament to narrow down the possibilities? I believe we can and, surprisingly enough, I think what we find vindicates a December birth for our Lord.
What we really need in examining this question is some fixed date, some event, to which we can "anchor" the events recalled in the Gospel of Luke. We already have a relative chronology: we know that Mary conceived our Lord six months after the conception of Elizabeth, for example. How can we anchor events such as the Annunciation and the Visitation to some concrete date or time?
The closest thing we have is the passage at the beginning of Luke's Gospel regarding the Temple service offered by Zachariah. Zachariah was a priest "of the division of Abijah" (Luke 1:5); this fact will be quite important. While in Jerusalem, "performing his priestly service before God in the appointed order of his division, according to the custom of the priestly office, he was chosen by lot to enter the temple of the Lord and burn incense. And the whole multitude of the people were in prayer outside at the hour of the incense offering. And an angel of the Lord appeared to him." (Luke 1:8-11) The angel Gabriel told Zachariah that his barren wife, Elizabeth, was to bear him a son, and his name was to be John. "And it came about, that when the days of his priestly service were ended, that he went back home. And after these days Elizabeth his wife became pregnant." (Luke 1:23-24)
If we go back to 1 Chronicles 24, we read that the houses of Aaron were divided up into twenty-four "divisions", each serving God in the Temple on a kind of rotation throughout the year (
see here). Abijah, the house to which Zachariah belonged, was one of these divisions. If we could find out when the division of Abijah was chosen to serve each year, we would know roughly the date of the conception of John the Baptist, and by adding fifteen months (Six of Elizabeth's pregnancy plus the nine months Mary was pregnant) we could get an idea of when our Lord was born.
The problem is that the Scriptures give us no data on when any certain division was on duty. For this, we have to turn to Jewish history and rabbinical tradition.
Josephus tells us that each division served from Sabbath to Sabbath, eight days, passing their duties on to the next division midday on the Sabbath (
Against Apion, 2:8). Each division ended up serving approximately five weeks throughout the year, though this got a little complicated during major feasts (during Passover, for example, all twenty-four divisions served at once). So, pinpointing when Abijah was on duty would give us five potential "windows" of eight days each throughout the year from which to extrapolate our Lord's birth.
But when was Abijah, or any order, on duty?
An interesting point of evidence is that, according to Talmudic tradition, the destruction of the first temple by Nebuchadnezzar in 587 B.C. happened while the family of Jehoiarib was on duty. This event was so deeply burned in the Jewish psyche that it is not surprising they would have remembered what family was on duty. Consider the following passages:
"Good things come to pass on an auspicious day, and bad things on an unlucky day. It is reported that the day on which the First Temple was destroyed was the eve of the ninth of Ab, a Sunday, and in the year following the Sabbatical year, and the Mishmar [division] of the family of Jehoiarib were on duty and the Levites were chanting the Psalms standing on their Duchan (platform). And what Psalm did they recite? - [The Psalm] containing the verse, `And He hath brought upon them their own iniquity, and will cut them off in their own evil.' And hardly had they time to say, `The Lord our God will cut them off,' when the heathens came and captured them. The same thing too happened in the Second Temple." (Ta'anith 29a)
"It is said, The day on which the first Temple was destroyed was the ninth of Ab, and it was at the going out of the Sabbath, and the end of the seventh [Sabbatical] year. The [priestly] guard was that of Jehoiarib, the priests and Levites were standing on their platform singing the song. What song was it? `And He hath brought upon them their iniquity, and will cut them off in their evil.' They had no time to complete `The Lord our God will cut them off,' before the enemies came and overwhelmed them. The same happened the second time." (Arakin 11b).
Now, if Jehoiarib was on duty on the 9th of Ab (July 18th), and we consult the order of the priestly divisions of the sons of Aaron as recorded in 1 Chronicles 24, we see that Abijah was the eighth division and Jehoiarib the first. This means Abijah would have been serving eight weeks after Jehoiarib. Since we have a fixed date on which to place the service of Jehoiarib (July 18th), we can extrapolate the whole cycle and figure out when Abijah was on duty.
Unfortunately, there are many complications to this method, the biggest being that the priestly schedule was disrupted several times. For example, it was disrupted at the time of the Babylonian Exile. For seventy years Ezra 6:15-18 tells us that Ezra and Nehemiah had to reconstitute the divisions on a new schedule after the return from Babylon and even had to create four new orders because four of the old orders had been lost. This schedule was again disrupted at the time of the Maccabees.
Fortunately, we have another reference to the order from closer to Jesus' life: the time of the Second Temple. Like the first destruction, the second destruction also occurred in July (28th) and again, according to Josephus, Jehoiarib was on duty. Despite the disruptions and the creation of new divisions, if we presume that each division at least retained its similar place in the order throughout this time, we can use this method, to find at least eight weeks throughout the year when Abijah would have been serving. They are not even intervals of eight weeks, due to the fact that Abijah would have been serving at major feasts besides the regular intervals. These weeks are:
Jan 18-25
March 19-26
April 18-25
May 17-24
Aug 3-10
Sept 3-10
Oct 3-10
Nov 1-8
Zachariah would have been offering incense during one of these weeks. The fact that a "large multitude" was gathered outside the Temple further tells us that the specific day was probably one of the great feasts, either Passover, Pentecost or the Feast of Tabernacles.
Now, if we presume that Zachariah heard the message of the angel and John the Baptist was conceived during one of these intervals, specifically on one of the great Sabbaths or high feast days, then by extrapolating fifteen more months, we have the following dates as possible times when Christ was born:
Jan. 23
Apr. 10
June 11
July 10
Aug. 8
Oct. 25
Nov. 25
Dec. 25
Note that December 25th is one of the eight possible dates. If this were Christ's birthday, this would place the Annunciation on March 25th (in accordance with Tradition) and the conception of John the Baptist in the vicinity of October 10th. This would place Zachariah's temple service during the week of October 3rd-10th, which actually coincides with the Feast of Tabernacles, which fell during the week of September 29-October 5th in 6 BC.
This explanation is fraught with difficulties. Of course it could have been December 25th, but this explanation also allows for seven other possible dates. And, these dates themselves are all based on extrapolations from some very scanty evidence, mainly a few passages from Josephus. That being said, greater minds than I have certainly came up with this before; it was originated by St. John Chrysostom, though there is even dispute about that (some saying that the work this is found in is spurious). And there is much more reckoning that needs to be done that I omitted for the sake of brevity - calculations of Sabbaths, new moons, etc. spanning centuries, which is why even the Catholic Encyclopedia
says such computations based on Zachariah's temple service are "unreliable" "untrustworthy" and even "hopeless."
Is December 25th really Jesus' birthday? There is now way to tell for certain, but at least we know that the traditional date is not without grounds. We certainly can say that December 25th does have a solid biblical and historic support and allows us to comfortably explain the date of our Lord's Nativity without reference to the Sol Invictus or winter solstice theories.
Here is a
good webpage with some more chronological information on Star of Bethlehem and further support for a winter nativity.