‘Tis more-or-less the Winter Solstice and at this time of year the merry Christmas tradition of arguing about when/why Christmas is December 25th can be heard rining down the frosted tubes of the internet. I’ll confess to have thrown around a few “Christmas is just a repurposed pagan holiday” a few times as part of festive festivities — it’s not a false argument but it does get overstated. Meanwhile, in far-right trad-catholic circles you’ll find a fair bit of the exact opposite argument: Jesus was definitely born on December 25. I’m going to look at this and also how the English financial year ties into Gollum biting Frodo’s fingers off.
I’ll deal with the last point first. No, putting aside questions of the historical existence of Jesus, nobody knows when he was born and that’s not even a recent idea. The 1908 Catholic Encyclopedia has an extensive entry on Christmas that points out:
“Christmas was not among the earliest festivals of the Church. Irenaeus and Tertullian omit it from their lists of feasts; Origen, glancing perhaps at the discreditable imperial Natalitia, asserts (in Lev. Hom. viii in Migne, P.G., XII, 495) that in the Scriptures sinners alone, not saints, celebrate their birthday; Arnobius (VII, 32 in P.L., V, 1264) can still ridicule the “birthdays” of the gods.”
Christmas is also celebrated on January 6 , January 7, and January 19 by different Christian groups and, of course, “Christmas” traditionally is a period of multiple holy days. Calendar differences mean it’s not even the case that different days indicate different dates. The Russian Orthodox Christmas (7 January) falls the day after the Western feast of the Epiphany because of differences between the Julian and Gregorian calendar (which I’ll get back to).
That we can’t know what the actually birth date of Jesus was or indeed that given the changes in calendars and dating that have happened since is something some people find challenging, despite it not being an article of faith in any significant version of Christianity nor being theologically that important. That doesn’t stop people trying though because, I guess, certainty is something people find solace in. One argument is that Jesus’s birth can be deduced from John the Baptist’s birth by working out when John’s dad was serving as a priest:
“Luke informs us that Zechariah, the father of John the Baptist, was a member of the course of Abijah, and was burning incense in execution of his priestly office when Gabriel appeared and announced that his wife would conceive a son. Based on statements in Luke, John was about six months older than our Lord (Lk. 1:36, 56). If it can once be determined when Zechariah was serving, and therefore when John was conceived, it is thus possible to identify the approximate time of Christ’s birth 15 months later.”http://www.dec25th.info/Unto%20You%20Is%20Born%20This%20Day.html
I don’t know enough about first-century liturgical practices in Judaism to know if that makes sense but firstly the margin of error there looks pretty big (“John was about six months older”) and the argument was regarded as unimpressive back in 1908:
“Arguments based on Zachary’s temple ministry are unreliable, though the calculations of antiquity (see above) have been revived in yet more complicated form, e.g. by Friedlieb (Leben J. Christi des Erlösers, Münster, 1887, p. 312). The twenty-four classes of Jewish priests, it is urged, served each a week in the Temple; Zachary was in the eighth class, Abia. The Temple was destroyed 9 Ab, A.D. 70; late rabbinical tradition says that class 1, Jojarib, was then serving. From these untrustworthy data, assuming that Christ was born A.U.C. 749, and that never in seventy turbulent years the weekly succession failed, it is calculated that the eighth class was serving 2-9 October, A.U.C. 748, whence Christ’s conception falls in March, and birth presumably in December. Kellner (op. cit., pp. 106, 107) shows how hopeless is the calculation of Zachary’s week from any point before or after it.”https://www.newadvent.org/cathen/03724b.htm
So there are two points of uncertainty to the dating: when Zachary was serving and how much older John was than Jesus. Of course, there is a third point of uncertainty — how long was Mary’s pregnancy but I’ll come back to that.
So given all that, why am I saying that “Christmas is just a repurposed pagan holiday” is overstated? Mainly because it looks like an explanation of why Christmas is on December 25 but it really isn’t an explanation. Yes, there are definitely significant days that fall on or near (depending on calendars) December 25 that were celebrated by non-Christians in Europe and specifically in Rome. I shan’t list them all but a key point in the year being the Winter Solstice, which we currently put at round-about December 21. However, the year is littered with significant days and if Christmas was held in a different (European) season other than Winter, you’d hit some other point. With two solstices and two equinoxes dividing the year into handy quarters and add in a couple of weeks either side, you have a third of the year covered. Nor are those astronomical points the only way of slicing the year into quarters.
Given that any newer holiday is likely to fall near an older holiday, it’s hardly surprising that newer holidays syncretically borrowed from older versions. So, yes Christmas has pre-Christian elements. However, those elements can’t explain why Christmas is the date it is because it would have pre-Christian elements whenever it was in the year. If Christmas was June 25 for example then it would be close to the summer solstice. Move it on several weeks and you have Lughnasadh. That doesn’t disprove that December 25 was picked to coincide with the birth day of Mithras or Sol Invictus etc just that an arbitrary choice would like as not fit near something.
To see how these calendrical shenanigans play out as secular authorities try to fit things into a crowded year, consider the English financial year for personal tax purposes. Just the name itself points to matters secular and distinctly ungodly and yet the date of it (April 6) brings us right back into the same issues of astronomical points, age-old holy days & holidays and duelling calendar systems.
When was George Washington born? That is surely an easier question to answer than when Jesus was born! And yet, the first President of the USA was born on February 22, 1732 and he was also born on February 11, 1731. He was a talented man but two birthdays (both correct) were a consequence of a calendar reform in 1750. Prior to that point, the official English year started on March 25 because that was the date of the Spring Equinox in the Julian calendar and the first day of the year in earlier Persian calendars. When Britain caught up with everybody else and reformed it’s calendar, several days had to be chopped off in the year the reforms where implemented. That shoved tax day forward to April 6 and also resulted in George Washington having two different birthdates (and everybody else who was born a British subject before the reform but died after the reform).
Notably, Tolkien worked that date into the Lord of the Rings, starting the Fourth Age of Middle Earth on March 25 as the date when the One Ring was destroyed i.e. Gollum Bites Frodo’s Finger’s Off Day. Which, I guess we should celebrate on April 6? I’m not sure. My broader point being that April 6 is UK personal tax day because of the Spring Equinox which is on March 20.
No, I haven’t wandered off topic!
Where was I?
Oh yes, Tolkien. He was a smart cookie and a Catholic and March 25 was not a date he plucked out of thin air. As well as being the Julian date for the (Northern Hemisphere) Spring Equinox it is also the Catholic Feast of the Annunciation. That holy day celebrates the conception of Jesus and lies neatly (and improbably) nine months before Christmas. The date also falls close to Easter making for a neat (or disturbing) idea that Jesus died on the anniversary of his conception. As a rationale for Christmas, this made a lot of sense to earlier Christians. The gospels were quite clear about when in the year Jesus died and so if Jesus died on the date he was conceived (out of aesthetic neatness) in March/April then he’d be born in December/January. It is neat but again, it is only speculation that this was the motive for assigning these dates.
The neat nine months between Feast of the Annunciation and Christmas Day is also rather neat. The cited figure for human pregnancies is 280 days but as anybody with any experience will tell you that is not a terribly reliable way of estimating what day birth will happen even if you manage to know when conception happened. 70% of people deliver within 10 days of their due date when pregnant  and so if we assumed March 25 as the date of conception, December 25 is both a reasonable and slightly unlikely date. Note that the earlier argument we met about the date of John the Baptist’s conception also implies an additional uncertainty of 37 days .
So when is Christmas? Christmas is a point in time in which people have agreed to celebrate. The rationales for the date are numerous and inconsistent but then so are the reasons for celebrating Christmas. Traditional 6/7 January is a long held date, either due to a different calendar or as the Feast of the Epiphany as a day for giving presents. As a day for giving presents St Nicholas’s Day is widely celebrated in multiple European/Christian traditions (variously 6, 7 or 19 December).
Am I saying that Christmas is a social construct defined by an intersubjective mutual understanding allowing us to coordinate social behaviour? Sure, I can’t thing of anything more festive than an intersubjective mutual understanding allowing us to coordinate social behaviour!
As the old carol goes: “May you all share your mutual understandings of when to coordinate celebratory behaviours with social groupings as best you can!”
-  Martindale, Cyril Charles. “Christmas.” The Catholic Encyclopedia. Vol. 3. New York: Robert Appleton Company, 1908. 22 Dec. 2020 http://www.newadvent.org/cathen/03724b.htm
-  https://en.wikipedia.org/wiki/Christmas_in_Russia
-  “The purpose of this site is to provide readers with evidence of Christ’s early winter birth so that they may celebrate Christmas day for the religious holiday it is” http://www.dec25th.info/
-  I’m picking British/Irish points but I’m confident you can find similar in other traditions because there are only so many days in a year https://en.wikipedia.org/wiki/Lughnasadh
-  https://en.wikipedia.org/wiki/George_Washington#cite_note-calendar-11
-  https://en.wikipedia.org/wiki/History_of_taxation_in_the_United_Kingdom#Why_the_United_Kingdom_income_tax_year_begins_on_6_April
-  https://en.wikipedia.org/wiki/Equinox#Date
-  https://en.wikipedia.org/wiki/Feast_of_the_Annunciation
-  https://www.sciencedaily.com/releases/2013/08/130806203327.htm
-  “even after we had excluded six pre-term births, we found that the length of the pregnancies varied by as much as 37 days” ibid
-  https://en.wikipedia.org/wiki/Saint_Nicholas_Day