Mithraism and Christianity: How Similar in Identity?
Among the first Christian apologists to respond to the phenomenon of the Mithras cult are Justin Martyr (ca. 100–165) and Tertullian (ca. 155–220). What most impressed these authors were the apparent similarities between their most hallowed religious rites and those of a cult that they considered idolatrous. How was such a thing to be explained? How could the Mithraists be celebrating a rite that had structures and patterns (e.g., banquet, gathering, sacrifice, etc.) similar to the eucharistic banquet celebrated by Christians? And how to explain the Mithraists’ apparent commitment not only to a form of baptism but also to a belief in a heavenly realm?
One can well understand how immediately challenging the Mithras phenomenon must have been to a profound thinker and theologian such as Justin Martyr. Unfortunately, however, the explanation he came up with in order to make sense of the phenomenon was far from inspired. Had he been able to examine more closely the Mithras phenomenon, Justin would no doubt have realized, as did Christian authors after him, how profoundly different it was, both in belief and practice, from his own religion. But the surface resemblances were, at first sight, so alarming that Justin felt constrained to come to the grim, unhappy conclusion that the rites were nothing but a mocking parody of Christian ritual, a deliberate device invented by the devil to disturb and confuse genuine believers. Likewise, Tertullian, writing half a century later—and believing, quite mistakenly, that the mysteries included such things as “the oblation of bread” and “an image of a resurrection”—repeated Justin Martyr’s theory. The devil, he wrote, is the one “who apes some of God’s things” to turn believers from their faith and “who vies even with the essential portions of the sacraments of God.”
The first great scholar of Mithraism, Franz Cumont, though not inclined to repeat the notion of a diabolical parody, was persuaded nevertheless that the rites practiced by the two religions “offered numerous analogies.” Like the Christians, he declared, the Mithraists “purified themselves by baptism,” they “expected from a Lord’s Supper salvation of body and soul,” and they “celebrated the birth of the Sun [Mithras] on the 25th of December, the same day on which Christmas has been celebrated since the fourth century at least.” This quite extraordinary depiction of the claimed resemblance between the two religions sounded so convincing that it gained widespread acceptance for many years. When, however, evidence for the claim came under close scrutiny by scholars, the Cumont theory began to look weak and unfirm. Although a few of the resemblances pointed out by Cumont remain convincing, such as the shared Mithraic and Christian emphasis on abstinence and self-control, other analogues proposed between, for example, the figures of Mithras and Christ, and between the two cults’ rites and practices, are now viewed with a skeptical eye by scholars.
Already in 1989 Leonard Boyle made bold to declare that “the resemblance between the two religions is entirely superficial. . . . The Mithraic ‘sacrifice,’ ‘last supper’ and ‘ascension’ seem to echo the Christian beliefs, but they belong in fact to a different world. The historical Christ and the legendary Mithras are as removed from each other as reality from myth.”
One of Cumont’s theories, dismissed eventually by most scholars as possessing no credible basis, is the notion that December 25, the reputed date of Christ’s birthday, is also the date of the birthday of Mithras. On this subject, Jaime Alvar writes in Romanising Oriental Gods, “It is fatiguing to have to clear away such mountains of continuously repeated misconception and error. There is no evidence of any kind, not even a hint, from within the cult that this, or any winter day, was important in the Mithraic calendar.” As for terms such as “baptism” and “salvation of body and soul,” which Cumont felt were applicable to both Mithraic and Christian practice, the feeling among scholars today is that Cumont unfortunately tended to project into Mithraic practice and belief Christian terms and categories that were not applicable.
The term “baptism,” for example, Jonas Bjørnebye points out, is “unattested in the Mithraic corpus of evidence.” Nothing, in other words, has been found to suggest a close resemblance between the Mithraic ablutions and Christian baptism. As for the term “salvation of body and soul,” which, according to Cumont, the Mithraists believed was in some way attainable through their own ritual practice of a quasi-eucharistic meal, “a Lord’s Supper,” Alvar writes, “There is not a shred of evidence that sacrificial meat in the cult was considered a manifestation of, or symbolic substitute for, the deity.” And he adds, “Our information about the Mithraic banquet is too poor to allow ourselves the luxury of attempting to reconstruct it by an appeal to the Eucharist.”
On February 27, 380, the Emperor Theodosius signed a decree that made Christianity the religion of the state, banning outright the practice of pagan rituals. That effectively marked the beginning of the end for all the mystery cults that had been popular in the early centuries AD. But here a question arises: Among all these religions, was the cult of Mithras perceived as a uniquely dangerous threat to Christian growth and flourishing? Ernest Renan, writing in the nineteenth century, notoriously remarked, “If the growth of Christianity had been arrested by some mortal malady, the world would have been Mithraic,” clearly indicating that, of all the Roman mystery religions, Mithraism was by far the greatest rival to Christianity. That view persisted for a good part of the twentieth century, the majority of scholars inclined to believe that so deadly a rival was the Mithraic cult to Christianity that it was, by the close of the fourth century, effectively persecuted out of existence.
But is this a true picture of what happened? Was Christian opposition the principal and determining factor in the decline of the Mithras cult? Or is it not perhaps the case, as Leonard Boyle and several leading scholars of the Mithras cult came to believe, that “too much has been made of the threat of Mithraism to Christianity”? Two factors in particular had, in the past, been given enormous weight: first, the manifest disdain for the cult voiced by a few notable apologists, such as Tertullian and Justin Martyr; second, the recorded instances of Christians desecrating Mithraea. Taking the last point first, there were indeed isolated cases of Christian iconoclasm, but according to David Walsh, “to assume that these accounts demonstrate an active conflict between Christian communities and the cult of Mithras would be misleading.” Why? One reason he gives is that “in reality there was little scope for Christians to actively persecute the Mithras cult given that the two groups operated in largely different areas.” Walsh adds, “Nearly all the works which claim that Christian iconoclasts were the driving force behind the damage and destruction of mithraea rarely attempt to ascertain whether there is any evidence of a Christian presence in the area at the time.”
But if Christianity was not the great destructive cause of the cult’s demise, how are we to explain that by the mid-fourth century the cult of Mithras had already begun to decline? Walsh offers three reasons. He has in mind, first of all, the fact that a very large number of the cult members of Mithras were soldiers in the empire. But, he notes, “as Roman hegemony became harder to maintain on the frontiers, the Mithraic cult found itself with an increasingly limited number of recruits upon which it could draw.” Second, there was a marked change in the social networks of potential Mithraic followers, and a new exposure to the attraction of other cults: “With mixed populations now living in much closer quarters and the distinction between military and civilian becoming increasingly blurred, it is not difficult to see why a male-only cult that had become bound up with Roman military identity might find itself decreasing in popularity.” Third, the Mithraic rituals by the beginning of the fourth century had become less and less demanding on new members. As a result, the bonds formed between initiates became much less strong. Instead of severe initiation rites, it was enough, apparently, simply to deposit coins on occasion in order to gain access to the Mysteries.
Step by step, the value of being a member of the cult was being undermined. By no longer placing “considerable demands” on its adherents, “the value of worshipping Mithras decreased.” Worshipers of the cult “felt less indebted to each other” and were “less likely to pull together to maintain their community during times of hardship.” In light of these facts, it would seem wise when trying to determine “the final fate of the mithraea” to examine critically the view of commentators such as Eberhard Sauer, who attributes the demise of the Mithras cult almost exclusively to Christian iconoclasm. Sauer’s thesis has been impressively challenged by none other than Richard Gordon, one of the cult’s foremost scholars. Gordon, as paraphrased by Walsh, points out that “many of the Mithraea that Sauer had looked at had failed to produce any convincing diagnostic evidence for Christian iconoclasm.”
Looking back over the years of debate on this question, Luther H. Martin, in The Mind of the Mithraists, notes that Leonard Boyle’s original “revisionist judgment minimizing any direct threat [from Mithraism] to nascent Roman Christianity” can now be seen as authoritative, being overwhelmingly supported by the evidence. “The actual conflict between Mithraism and Christianity,” according to Bjørnebye, “was minimal, contrary to what the rhetoric of Jerome and Prudentius would have us believe.” Furthermore, the close social interaction between Christians and non-Christians implies that “there were other modes of interaction at play between the two than fierce competition.”
When Christianity and Mithraism did, in fact, encounter one another, according to Bjørnebye, “the two religions lived side by side in relative harmony, peacefully for the most part.” If what Bjørnebye is saying here is even partly true, and if the scholarship of authors such as Walsh, Gordon, and Martin is to be given credit, then Mithraism and Christianity were not, as has so often been claimed in the past, such fierce, deadly rivals.
From Pagan Temple to Christian Basilica
Next to the domus in which was housed the Mithraic temple, there stands a large tufa-block building whose identity has long puzzled scholars. Generally referred to as a horreum (storage building), this structure is now thought most likely to have housed the Roman mint, a place connected in Roman mythology with the goddess Juno Moneta, the patroness of the funds of the empire. From her name derive the English words “money” and “mint.” In time, the horreum, together with the domus next door with its temple to Mithras, would be filled in with bricks and debris, and on top of both structures a Christian church, the Basilica of San Clemente, would be erected. But the building phases leading up to the construction of the basilica would prove, according to Juhana Heikonen, to be “as complicated and interwoven as one might expect in a city like Rome.” How these various phases eventually developed into the famous basilica has become the subject of much debate.
The horreum was the first of the two buildings to undergo radical change, and this happened at a time, mid-third century, when the Mithraic temple next door was still in use. After the first floor of the horreum had been pulled down, all the rooms at ground level were filled up with rubble. A new space was thus created and, eventually, in that space, a new building also. But what kind of building was it? What was its function, its character? On this question, Heikonen writes, “The function of the new building is still not known, and the remains of this phase are scarce. What we do know, according to Federico Guidobaldi, is that it had a rich decoration, having a central space surrounded by a narrower aisle on three sides. The remains of a rich opus sectile pavement point towards something more than just another factory or storage space.” It might well, in Guidobaldi’s opinion, have been a domestic dwelling, a private rather than a public building. It is also possible that it may have served as an early Christian gathering space. But the archaeological evidence itself offers no clear indication as to the exact function of this third-century building.
How, by the end of the fourth century, this Roman domus became transformed into the Basilica of San Clemente is a question that has been explored with particular focus by three outstanding scholars: the most recent, Federico Guidobaldi (to whom reference has already been made), E. Junyent, and Richard Krautheimer. Guidobaldi is now generally regarded as the greatest authority on the architectural history of San Clemente. Relying for the most part on the work of Guidobaldi, Heikonen—a younger, more recent scholar—looks afresh at the relation of the domus to early Christian architecture. In light of topographical, architectural, and socioeconomical considerations, Heikonen concludes that the first building phase of San Clemente was an aula ecclesiae—“a church, that is, constructed in the public space of a domus.” The domus may at some stage have been a center for Christian worship, the service most likely “divided,” it is thought, “into two parts: a reading of the Holy Scripture, open to everyone, and the Eucharist, which was for the baptized alone.” With the passing of time, however, there was a felt need in Rome for “larger meeting places.” As a result, according to Heikonen, we witness the development from “private dwellings to larger places of Christian worship (domus ecclesiae) up to the aula ecclesiae which could hold more people but was not a proper basilica.” When, by the late fourth century, the Mithraic temple next door had ceased to function, the property was acquired by the Christian authorities. It was now possible, over that abandoned area, to extend the length of the aula ecclesiae, and thus provide a firm foundation for an apse in the newly constructed Basilica of San Clemente.
EDITORIAL NOTE: This article is excerpted from Majesty and Beauty: The Basilica of San Clemente and Its Underworld (Word on Fire, 2026). All rights reserved.
