Did Christmas Copy the Sun God’s Birthday?

The sun. Every second, it fuses 600 million tons of hydrogen, bathing the earth in the energy that makes life possible. And although around 5.4 billion years from now, the sun will exhaust the last of its hydrogen and lose much of its mass as it dwindles into a small white dwarf star, the sun as it appears right now looks to be well invincible. And thus, the Roman sun god is well named: the invincible sun, the unconquerable sun, Sol Invictus, or Sol Invictus for those of you who prefer the classical pronunciation.

Every year, around Christmas, Sol Invictus is brought out as an example of how Christians tried to conform their new religion to the pagan landscape of the Roman empire. As one version of the argument goes, Sol’s birthday was celebrated on December 25th, thus Christian authorities mandated that Jesus’s birthday would also be celebrated on December 25th, perhaps in an effort to co-opt an already popular pagan festival day for themselves, either to directly compete against the cult of Sol Invictus or perhaps as a conversion or proselytizing strategy. Different motivations are put forth, but does this theory hold any water? I’ve addressed this topic before on the channel in passing, most notably in my Saturnalia video and my Why December 25th video, but I’m aiming for this video to stand as a more thorough-going analysis of the Sol Invictus theory.

While we do have limited evidence that the Romans marked December 25th as the birthday of Sol Invictus, this evidence indicates it was not a major festival or a particularly long-standing festival when compared to other Roman holidays. In fact, as we’ll examine later in this video, our evidence that Christians started recognizing December 25th as Christmas may pre-date the institution of Sol Invictus’s birthday by a few decades. But it’s even more complicated than that. The sun probably is the reason why anyone celebrated anything on December 25th, because that’s the day that the Romans marked the winter solstice, the shortest day of the year in the northern hemisphere.

In this video, I will argue that the more likely reason that December 25th became a contender for Jesus’s birthday was the result of Christian chronographers attempting to calculate the key moments of Jesus’s life using the ambiguous and even contradictory data available to them in the gospels: when was he conceived, when was he born, when did he die? Based on evidence dating back to the third century, many Christians, especially in the western Roman empire, embarked on a complicated calculation spree to try to nail down these dates. For Jesus’s birthday, some eventually settled on the winter solstice, December 25th, and for his conception and death, they settled on March 25th, which happened to be the vernal equinox for the Romans. This was no accident.

I’m using the word calculations here, but the word contrivances might be a better word to describe what these Christians were doing. These Christian chronographers were probably motivated to align their calculations with these two dates because of their poetic cosmic symbolism, but there is no direct evidence that they calculated these dates in an attempt to copy or co-opt a pagan festival. For the pagans, the shortest day of the year in the Roman empire also made a lot of sense for a festival for the sun god because the days get longer and longer after that day. So the December 25th date was not so much a battle to usurp the day from the pagans, but rather evidence that there were parallel traditions tying their own god to an already significant day, the winter solstice. Note that we will not be addressing specific christian observances like christmas trees and gift giving, but will be focusing simply on the question of possible influence from a sun god festival during the Roman empire.

With all of that out of the way, let’s get into the evidence by first laying some groundwork: who was Sol Invictus in the first place? Let’s start with his iconography so you’re equipped to recognize the sun god in Roman art. How did Roman artists depict Sol Invictus? We learn his appearance largely from Roman mosaics, paintings, and small finds like figurines and Roman coins. He is almost always depicted as a young male figure, usually nude except for a cloak, and at least in the Roman era, he is always beardless. The leading scholar of the Roman sun god, Steven Hijmans, definitively says in his book, “A bearded figure cannot be Sol,” and indeed we see this on countless depictions, from figurines to paintings to coins. As for headgear, he either wears a spiky crown symbolizing sun rays or has a nimbus of light rays around his head, very apropos for a sun god.

Taking a page from Greek mythology, he’s frequently depicted as the driver of a four-horse chariot called a quadriga. He’s also sometimes portrayed holding a whip or a globe, other times depicted raising his right hand as cosmic deities. The moon god frequently appears beside Sol as some sort of consort, which you can see here on screen with this late Roman amulet which depicts the sun and moon gods side by side. Finally, Sol also sometimes appears with the god Mithras, as we’ll discuss shortly. His name Sol simply is the Latin word for sun, while Invictus is an epithet, which is an adjective that expresses a quality or attribute of the sun, in this case, invincible or unconquerable.

As we’ll see later in this video, an earlier generation of historians tried to argue that Sol Invictus was a specific sun god, specifically an eastern sun god from Syria or Persia, but as Steven Hijmans argues, Invictus is simply one of many Latin epithets that can be given to Sol as well as many other deities without fundamentally changing their identity. In fact, the epithet Invictus was used for hundreds of years for both Roman emperors and other gods. Emperors like Trajan, Commodus, and Caracalla called themselves Invictus, as were gods like Jupiter, Mars, and Apollo. There are even coins that mention Hercules Invictus. So throughout this video, I use sun god or Sol with or without his full title Invictus because the Romans themselves did not use the word to refer to a specific sun god or a specific sun god cult.

Now as we transition into a basic history of the Roman sun god, three themes will emerge: he was a relatively minor god, he was a multi-valent god associated with several different deities, and our evidence for this god’s veneration and the rituals performed for this god is not as good as we’d like. None of his temples survive in the archaeological record, and our written sources rarely mention what cultic practice might have looked like. This includes any sun god festivals. Unlike Saturnalia, a Roman holiday that is very well attested in Roman literature, we have very little data describing sun god festivals in the Greco-Roman world. People worshipped a sun god for centuries, albeit as a relatively minor god. The sun god only enjoyed major support during the later Roman empire.

For the Greeks, the sun god was Helios, and he has a long history in Greek mythology. The son of the titans Hyperion and Thea, he is mentioned in some foundational Greek stories including the Odyssey as well as some of the Homeric hymns, though he remained a somewhat minor god in the Greek pantheon. Greek authors such as Pausanias do mention a few cultic centers of Helios worship, but he was outshone by gods with big panhellenic sanctuaries, like Apollo with his cultic center in Delphi or Zeus with his cultic center at Olympia. Historians used to argue that the Romans simply copied the Greek Helios for their own sun god, though the experts on this topic now argue this is inaccurate.

The Romans did meld some attributes of the Greek Helios, and Roman writers do equate Helios and Sol. The emperor Julian, for example, who is called the Apostate because he tried to reinstitute traditional Roman religion during the christianization of the Roman empire, simply refers to the sun god as Helios in Greek, though it’s pretty obvious he’s referring to what Latin speakers would have called Sol Invictus, because he explicitly says Helios nicknamed invincible. So this is our first example of the sun god being a multi-valent character: Helios in the Greek-speaking world, Sol in the Latin-speaking world. But the Romans appeared to have originally worshipped some sort of native sun god during the Roman Republic.

Sol apparently was a minor god who was worshipped in tandem with the moon god Luna. The Roman writer Varro, who lived during the second and first centuries BCE, claims that Sol was worshipped as far back as the mythical founding of Rome around the time of the legendary king Romulus, though we shouldn’t take this as historical. It might suggest that the Romans worshipped a native sun god as far back as they could remember in their history. And though the archaeological evidence for sun god cultic practice is sparse, our sources suggest that shrines and temples to Sol were built in the urban core of Rome. Tacitus, writing in the late 1st or early 2nd century, says that an old temple to Sol stood in Rome near the chariot racing stadium called the Circus Maximus, though it doesn’t exist anymore and we have no idea what it looked like.

This leads us to the second point that I mentioned: when it comes to trying to reconstruct the ancient cult of Sol, and by cult I mean practice and the rituals people did, our sources are not that great. As Steven Hijmans remarks in his definitive book on the subject, most of what the Romans said about the sun god consist of elite members of society writing philosophical musings, writing treatises on cosmology, astrology, and the nature of the sun. But philosophy is not ritual practice. These writers don’t say much at all about how Sol Invictus was worshiped, what rituals were conducted, or what festivals were celebrated, and archaeology doesn’t really help because his temples and shrines have not survived to the modern day. Mostly we just have artistic representations and small finds like figurines and coins.

As I said before, things are further complicated by the fact that the sun god is often conflated with other gods, not only the Greek Helios, but also Apollo and Mithras. Apollo frequently was depicted as a solar deity with sun rays emanating from his head. Sometimes Roman writers equated Sol with Apollo, other times they’re treated as separate deities. For example, the late Roman writer Macrobius argued that Apollo was just another name for the sun god. Mithras is also an interesting case. Now I won’t go too deep into the cult of Mithras as I’ve already done another video on the topic, but briefly, the cult of Mithras was a mystery cult, a religious group that required you to go through an initiation process to join, and as the name suggests, it revolved around a romanized version of the persian god Mithras.

No literary narratives survive from Mithraists that could tell us what they thought about the god or the god’s mythological backstory. The only written texts we have are inscriptions and passing references and texts written by outsiders. But from what we can piece together from the religious iconography in Mithraism, the religion was strongly influenced by astrology and solar imagery. Mithras himself is sometimes called Sol Invictus Mithras, but a separate sun god also appears in Mithraic iconography. Mithras and Sol are portrayed in the same scene, sometimes banqueting together, sometimes riding a chariot together. So even though we don’t know the myths that stand behind these images, we do know that the sun god must have played an important role in the mythology of Mithraism.

Another tricky thing about Sol is that he’s both a god and a cosmic symbol, obviously symbolizing the sun. In other words, the word Sol can be a proper name referring to an anthropomorphized god or just the word for that big shiny ball in the sky, and so Sol continues to be an ambiguous figure. A good example of this is that the sun god appears as decoration on the floors of a few late antique Jewish synagogues. The example here on screen is the Beit Alpha synagogue near Beit She’an in northern Israel. It depicts Helios galloping towards you with his four-horse chariot. Here’s another example: some footage I took at the synagogue uncovered at Sepphoris in northern Israel located near Nazareth. A radiant sun disk sits above a four-horse chariot, also meant to depict Helios, but in a non-anthropomorphized form.

Judaism is famously monotheistic; the Hebrew Bible has the commandment “You shall have no other gods before me,” the God of Israel. It’s also famously aniconic, meaning without image or without icon, thus the commandment “You shall not make unto thee any graven image.” So why is there a pagan god in these synagogues? Ever since these synagogues were discovered, scholars have debated this question. I tend to agree with the historian Steven Fine, who argues that the image of Helios in these synagogues does not suggest he was venerated by late Roman Jews. The ritual context matters: he appears as floor decoration and not a sacred image within a shrine, which would indicate some form of ritual veneration.

Another interesting example is the appearance of the sun god in what is probably a Christian tomb discovered in the Vatican. Even though this tomb was fairly small, it was jam-packed full of Christian art: Jonah on the east wall, the Good Shepherd on the west wall, and on the ceiling, we have an image of the sun god. By any other metric, this is Sol. He’s beardless, he has sun rays emanating from his head, he holds a blue globe, he is raising his right hand, and he’s driving a four-horse chariot. These are all of the same attributes that we analyzed before. Some have theorized that this is meant to represent Jesus dressed as the sun god, thus it’s sometimes labeled as Christ-Helios.

Now Steven Hijmans, who’s probably the leading expert on Sol Invictus, is very skeptical. He argues there is nothing self-evidently Christ-like about this image; it is clearly a standard depiction of the sun god, and it’s put on the ceiling because, well, the sun is directionally up. I used to think that this was Christ-Helios as well, but my opinion on this matter has evolved. I tend to think of this image in the same light as those synagogues now, demonstrating that Christians may not have been so squeamish about using pagan symbols, especially if those pagan symbols are removed from a cultic context like a temple or a shrine. In these examples, it’s likely that Sol is not so much an object of worship as much as a personification of the sun, no more ritually significant than placing a personification of freedom on top of the US Capitol.

This evidence illustrates, as Hijmans argues, the sun played an ambiguous role in the Roman world, both as a cosmic body and as a god, and because of this cosmic symbolism, Christians and Jews could deal with Sol as a symbol without necessarily dealing with the pagan god Sol Invictus. From the previous discussion, we’ve learned that the Roman sun god had many forms, variably equated with the Greek Helios, Apollo, or Mithras, and sometimes considered just as a cosmic symbol. We’ve also learned that for most of Greek and Roman history, he was a minor god, and very little evidence survives that indicates how he might have been venerated. But in order to assess the Sol Invictus Christmas theory, we need to lay a bit more groundwork.

Although he was a relatively minor god for centuries, everything changed in the third century because of this guy and this guy: the Roman emperors Elagabalus and Aurelian. The year is 218 CE, and a teenager by the name of Varius Avitus Bassianus ascends to the throne of the Roman empire. By then, he had already spent some time as a priest of the Syrian sun god Elagabal and earned the nickname Elagabalus. The cultic center of the sun god was located in the city of Emesa, now located in modern-day Homs, Syria. Even though Sol is frequently associated with other gods like Apollo, Elagabal is a different sun god. As we discussed earlier, while the Roman sun god was portrayed as a nude young man with a radiant crown, this god was depicted in the form of a black stone, possibly a meteorite.

The Roman writer Herodian says this stone is worshipped as though it were sent from heaven; on it there are some small projecting pieces and markings that are pointing out which the people would like to believe are a rough picture of the sun. This stone is depicted on some Roman coins minted early in the reign of Elagabalus, and curiously, they even depict this stone riding around in a four-horse chariot, replacing the usual human figure of Sol Invictus. As his nickname suggests, Elagabalus was an ardent devotee of this Syrian sun god, and he tried to establish this god in Rome. Like we just saw, he minted new coins with Elagabal, he instituted festivals and games, and was reported to walk around dressed like a priest of the sun.

The Roman elite were not happy. The historian Dio Cassius writes that he offended Roman tradition not in introducing a foreign god into Rome or in his exalting him in very strange ways, but in placing him even before Jupiter himself and causing himself to be voted his priest. Ultimately, his efforts failed. Elagabalus was eventually assassinated, and his new sun cult fizzled. That might have been the story of Sol if it were not for Aurelian a few decades later, who rose to power in 270 CE. Aurelian was also a devotee of the sun. According to the fourth-century text Historia Augusta, Aurelian miraculously defeated Queen Zenobia of Palmyra in 272 CE. After his victory, he fulfilled a vow at a temple to our familiar friend Elagabal in Emesa, Syria.

He went a few steps further back in Rome: he built a new temple to the sun god, instituted a college of high-ranking priests for the sun god, and he also instituted public games to be held every four years, basically the sun god Olympics. We’ll return to these games shortly, but for a bit of a spoiler, scholars now debate whether or not he instituted these games on December 25th. No ancient source explicitly says he instituted a holiday on December 25th, and though it’s very possible, any historian that says so definitively is only inferring this rather than basing the argument on direct evidence. It’s also likely he expanded an already existing sun god festival on October 19th, but we’ll get back to that soon.

Aurelian’s story sounds familiar to that of his predecessor, emperor Elagabalus. After all, he visited Elagabal in Syria, and historians throughout the twentieth century argued that Aurelian was trying to revive the same sun god cult. The traditional argument went something like this: the Romans worshipped a relatively low-profile native sun god called Sol Indiges, but that cult eventually fizzled out. Roman emperors such as Elagabalus and Aurelian later introduced a completely new, distinct Syrian sun god called Sol Invictus. But historians largely reject this two-sun-god theory these days, thanks in large part to the work of Steven Hijmans.

He argues convincingly that this theory exaggerates the effect of Elagabalus. Remember that he was resisted and finally assassinated by the Roman elites, and his efforts to introduce the Syrian Elagabal failed within four years. It is not plausible that his four-year effort had any lasting effect on the religious landscape of the Roman empire; no emperor can just flip a switch and make everyone worship a new god. Aurelian definitely boosted the sun god’s popularity a few decades later, but the evidence suggests that Aurelian was not trying to revive Elagabalus’s efforts, but rather was just continuing a long tradition of sun god veneration in Rome that stretched back hundreds of years.

Sol was already popular within the Roman military, corroborated by inscriptions of Roman soldiers fulfilling vows to Sol Invictus as far back as the second century, decades before Elagabalus, and Roman emperors were stamping their coins with images of the sun god since the reign of Vespasian, basically 150 years before Elagabalus. In fact, Sol appears on Roman coinage almost annually starting from the reign of Commodus, and this practice continued all the way through Constantine’s reign. During this time, Sol’s iconography remains relatively unchanged. During Aurelian’s reign, the sun god is portrayed anthropomorphically in the traditional Roman style, and not as a rock like what we see under Elagabalus.

In other words, there is nothing particularly Syrian or persian about Aurelian’s Sol Invictus, and as I mentioned earlier in this video, an earlier generation of historians put a lot of emphasis on that epithet Invictus, saying that the native sun god was called Sol Indiges, so any time you see the name Sol Invictus, it must be referring to the Syrian version introduced by Elagabalus. But this is simply not the case. In fact, inscriptions predating Elagabalus mention Sol Invictus, so it’s a mistake to think that Invictus refers to a specific version of the Roman sun god, let alone an eastern sun god that Elagabalus tried to introduce.

What happened under Aurelian? Based on imperial coinage, it seems that from the reign of Trajan, the Roman sun god was associated with battles and victory, and was popular in the Roman military, and was associated with the Roman emperors. Aurelian elevated the importance of the sun god during his reign, apparently following this tradition of battle victories. Aurelian likely considered Sol Invictus to be a patron god to him personally and his family in general, and in the following decades, Sol Invictus remained closely associated with the Roman emperors all the way through emperor Constantine the Great. Aurelian’s devotion to Sol Invictus has been misconstrued as some form of solar monotheism, but he was by no means replacing other gods.

Aurelian instituted a new college of priests, which raised the social standing of the sun god cult in Roman society because it would have drawn its members from the Roman elite, but this college did not replace other colleges of priests. Case in point: on one hand, Aurelian minted coins that labeled Sol Invictus lord of the Roman empire, but he also minted coins around the same time that show Sol handing a globe to Mars Invictus. So he raised the profile of Sol, but this was definitively not solar monotheism. This popularity continued into the reign of Constantine the Great, who was probably most famous for showing favor to Christianity after experiencing some sort of conversion.

Before turning to Christianity, Constantine was a devotee to the sun as well. According to one source, in 310 AD, two years before the battle of Milvian Bridge when Constantine rose to power, Constantine stopped at a temple of Apollo with his army and claimed that Apollo appeared to him in a vision prophesying that Constantine would live a long life and rule the world. Now as we’ve seen, Romans often associated Apollo with the sun and even identified him as Sol Invictus, and it seems Constantine equated the two as well, and even after his conversion, Constantine continued to interpret Jesus and the christian God through his solar theology. If you want to learn more about Constantine’s conversion, I talk more about this in another video.

All right, so what does all of this have to do with celebrating Christmas on December 25th? I spent so much time laying the historical groundwork because it’s really important to understand what happened before, during, and after the third century. The third century was a major turning point for the sun god. It was not until around 274 CE under emperor Aurelian that the sun god was institutionalized in the highest levels of Roman government and viewed as an imperial patron god. Now, as a history major in college, I’m the first to say that dates are not the most important thing about history, but I really want us to pay attention to the dates in the next section.

With 274 CE as our hinge point marking when the Roman sun god became anything more than a minor god in the Roman religious landscape, the questions that are important here are: when did Romans start marking December 25th as a birthday for Sol? How important was that festival? When did Christians start making December 25th as a birthday for Jesus? How important was Sol Invictus and his festival in making that decision? Let’s start with the first two questions. Steven Hijmans strongly stresses that December 25th was neither a long-standing nor an especially important official feast day of Sol. I’m going to say that again: December 25th was not a long-standing nor an especially important official feast day of Sol Invictus.

You should probably have already guessed this based on the previous historical overview. The sun god was a minor deity until the late third century; we simply don’t know when December 25th entered the Roman calendar as a holiday for Sol Invictus. It might have been 274 under Aurelian, and I actually think that’s the case, but our clearest ancient evidence that explicitly mentions December 25th as a birthday of Sol Invictus is found in the so-called Chronograph of 354, which, as the name suggests, is a compilation of chronological texts composed or compiled in 354 CE, 80 years after Aurelian. One of the documents included in this compilation is a calendar listing the festivals that were celebrated in the Roman empire in the mid-350s.

A single line in the month of December names December 25th the natalis invicti, or the birthday of the unconquered, and it says that on that day 30 chariot races are to be held in celebration. The text on screen is how it appears in the calendar: a single line mostly consisting of abbreviations. The Roman numeral VIII stands for eighth day before the kalends of January, or in other words, December 25th; N stands for natalis; CM stands for circenses missus, 30 games ordered. It should be noted that this word natalis is confusing. Very simply, it can be translated as birthday, but as the scholar Michele Salzman argues, it can also simply refer to a celebration to honor a god or the anniversary of the dedication day of a god’s temple.

Salzman argues that this day marked the day that emperor Aurelian dedicated his new temple to Sol in the 270s. Now remember that she’s extrapolating; this is not direct evidence, but I think it’s a convincing extrapolation. So this answers our first question: when was this holiday instituted? It appears to be at least 274 CE. We have no evidence of a sun god festival held on December 25th before this calendar date. Moving to our second question: how important was this festival? What’s interesting is that this same calendar mentions two additional sun god holidays. It mentions a multi-day festival for Sol celebrated from October 19th to the 22nd called Ludi Solis, or the games of Sol, which is to be celebrated with 36 chariot races, as well as a festival for the sun and moon on August 28th.

The Ludi Solis are interesting because they coincide with an older Roman holiday on October 19th called the Armalustrium, a military festival associated with Mars, when Roman soldiers arrayed themselves in the Circus Maximus, a location where we’ve already learned was associated with the sun god. The August 28th holiday is interesting too, because according to early imperial sources, Sol’s feast days were on August 8th, 9th, 28th, and December 11th, and as you’ll notice, of these dates, only August 28th is mentioned in the calendar of 354. This suggests that older festival days eventually were dropped, and the longest-standing festival day for Sol Invictus appears to be August 28th.

Also, as an aside, it’s important to note that December 25th does not appear in this oldest evidence, and thus is probably a more recent innovation. So looking at the calendar of 354, it’s not all that clear which one of these holidays is the most important Sol Invictus festival. August 28th is the oldest, stretching back to the early centuries of the Roman empire; the Ludi Solis are the biggest in the terms of celebrations, a multi-day festival with 36 chariot races that probably was inspired by the older Armalustrium holiday; while the birthday on December 25th sits somewhere in the middle, a single-day festival with 30 chariot races.

All this to say, it’s not accurate to suggest that December 25th was the Sol Invictus holiday. This source does mention it as the sun‘s birthday, but it was potentially overshadowed by these other holidays, particularly the multi-day festival starting on October 19th. So imagine you’re a Christian living back then, and you were going to try to compete with Sol Invictus or even try to co-opt or neutralize Sol Invictus celebrations with a Jesus-themed celebration. From my perspective, there is no compelling reason from the evidence to single out December 25th when an equally big, if not bigger, festival was celebrated in October. And of course, it’s worth mentioning that this calendar of 354 is a thoroughly Christian document.

After all, it dates to 354 CE, decades after Constantine legalized the religion and started boosting it. This same calendar includes a list of the burial dates of Christian martyrs and bishops; the calendar also includes dates on when to celebrate Christmas and lists December 25th as Jesus’s birthday. So this calendar makes me doubt that most Christians were all that threatened by pagan festivals in general or Sol in particular. So our best and clearest evidence of a supposedly very popular pagan festival—a festival so important that Christian authorities felt threatened or at least compelled to declare it the birthday of Jesus—comes from a single line in a Christian document dating 40 years after Christianity had already been legalized in the Roman empire.

Another source that explicitly mentions a solar festival in late December is emperor Julian, nicknamed the Apostate for his rejection of Christianity. In 362, in a text on Helios, he writes: “Before the new month, immediately after the end of the month Cronos, we celebrate the most splendid public game in honor of Helios, the feast for Helios nicknamed invincible.” Even though this quotation is very short, it does demonstrate that Romans were still celebrating public games and feasting on a late December sun god festival, which tracks with the calendar of 354, though again this evidence is quite late.

So let’s review the evidence: Aurelian boosted the sun god’s importance in 274 and is said to have introduced public games; the calendar of 354 mentions 30 chariot races held in honor of Sol on December 25th; then in 362, emperor Julian briefly mentions public games and a feast held in late December for Helios. Returning to our first two questions: when did Romans start marking December 25th as a festival for Sol Invictus, and how important was that holiday? The answer to the first question is we don’t know, but based on this evidence, it may have been instituted under emperor Aurelian in 274. By the fourth century, it apparently was celebrated with feasting and chariot races, and it was one of several holidays for the sun, specifically August 28th and the October games.

This is basically all we know, which means the answer to the second question—how important was this holiday?—is difficult to answer. It probably was not as important as the other December holiday, Saturnalia, for which we have tons of evidence, and maybe not even as popular as the other Sol Invictus festivals in August and October. The lack of evidence leads three leading scholars on this topic to seriously question whether the natalis invicti celebrations on December 25th were really so ancient, widespread, and momentous as to exert a strong influence on Christian communities during the formative development of the holiday celebrating the birth of Jesus Christ.