The conversion of the Roman Empire to Christianity

Christianity was born in the midst of an occupied nation, often despised and subjected to the most powerful empire of its time. From the very first decades of its existence, it was considered an "illegal" religion. The mere fact of being a Christian could lead to a death sentence. In every generation, the main leaders of the Church were executed by the political authorities. However, during the first three centuries, the Church continued to grow and, in the fourth century, she even triumphed over the pagan empire that persecuted her. Such success is unique in history. The publication of an edict banning all pagan sacrifice and worship on November 8, 392, is remembered as the date when Christianity was established as the state religion within the Roman Empire.

Detail from Raphael's Vision of the Cross, 1520, Vatican Museums / © CC0/wikimedia

Reasons to believe:

The rise of Christianity in the Roman Empire is a unique phenomenon in history. After three centuries of illegality, Christianity finally completely supplanted official paganism. The conversion of the Roman Empire to Christianity has been described as "miraculous" by Saint Augustine.

The universal love advocated by Christianity was profoundly innovative. The beauty of Christian doctrine itself touched the hearts of pagans, who were able to recognise the truth of this teaching, thus provoking numerous conversions.

The atheist historian Paul Veyne examines the causes of this religious triumph. He explains it in particular by the person of Jesus and the superhuman authority that emanated from him.

Providential events prevented the pagans from bringing their plans to fruition. One example is a storm that led to Emperor Theodosius the Great's decisive victory over the rebel Augustus Eugenius, who favored the old Roman gods, in the Battle of the Frigid River (September 6, 394).

The martyrdom of successive Church leaders (even though it was easy to remain free if one abjured Christianity) is proof of the veracity of the apostolic witness. If the apostles had not witnessed the Resurrection of Christ, they could never have accepted to die for him.

Numerous miracles are also attested. Here again, it is difficult to imagine that all these witnesses would have died for a lie.

Summary:

Jesus was born among the people of Israel, who were at that time subject to the Roman Empire, the greatest power of the time. Because of their own laws, in particular circumcision and dietary prohibitions, this people was despised by a number of pagans. Jesus preached in Aramaic, a language spoken only by people considered "barbarians" by the Greeks and Romans. He died crucified, the most shameful punishment in the Roman Empire. However, three centuries later, the very head of the empire, Constantine, eventually converted (around 312), recognising that Jesus was indeed the Son of God. This conversion marked the beginning of a process that would culminate, at the end of the century, during the reign of Theodosius, in the conversion of the Empire itself. How can such a reversal of fortune be explained?

St Augustine had already stressed the miraculous nature of this conversion. In his book Quand notre monde est devenu chrétien (312-394), the historian Paul Veyne acknowledges, despite his avowed "unbelief", that "Christianity is a global masterpiece". Wondering how to explain this triumph, he points to two essential causes: a religion of love, which was original at the time, and the superhuman authority emanating from its master, the Lord Jesus. In other words, the person of Jesus and his doctrine.

First, the person of Jesus: From a purely human point of view, his story had nothing to attract the Greco-Roman population. On the contrary, crucifixion was the most shameful death there could be, and the ultimate proof that this story could not have been invented. His Resurrection also seemed an insane idea in the eyes of the dominant philosophy of the time. Yet these two facts provide Christians with an essential force for proclaiming the Gospel, since it removes their fear of death and leads them to accept martyrdom. Many of the disciples who met the risen Jesus died for him. Now, even on the unlikely hypothesis of a widespread lie, it is even more improbable that so many people were willing to die for it.

The same applies to miracles. Jesus himself and his apostles performed many miracles. After his death, subsequent generations testify that God was still performing miracles within the Church. Although it is impossible to prove all these accounts individually, we can think that a generalized lie is again implausible. If the people who testified to these miracles had lied, they would probably have preferred to save their lives, if only by offering a little incense, rather than suffer martyrdom.

The second point raised by Paul Veyne is the innovative nature of love. It's important to remember this, because even though we live in a "post-Christian" society today, we are so used to the moral values of Christianity that we tend to forget that it wasn't always like that. Paganism was unaware of this bond of love between a divinity and human beings, or this call for universal love. The beauty of this doctrine touched the hearts of many who recognised the truth of this teaching. But it also had social consequences that led to the conversion of many individuals.

One of the most visible examples is the attitude of Christians during epidemics. Whereas pagans, to avoid dying, abandoned the sick, Christians, driven by the hope of the Resurrection and love of neighbour, did not hesitate to risk their lives to help the sick, in particular by providing them with something to eat. And even if the medicine was rudimentary, in many cases this help with food gave the sick the strength they needed to survive the illness. Christians therefore probably had a better survival rate than pagans, and pagan survivors who benefited from Christian aid were more likely to convert to Christianity.

Another consequence of this love can be seen in Christian morality, particularly with regard to infanticide. In ancient times, abandoning children, especially little girls, was morally acceptable. Plato and Aristotle legitimised it. Abortions were also carried out, regularly resulting in the death of the women concerned. On the scale of the Roman Empire, this posed major demographic problems. Ancient authors such as Dion Cassius pointed out the lack of women, but the political authorities were unable to provide any solutions because they endorsed the morality behind these practices. Christianity, in the tradition of ancient Judaism, is categorically opposed to this. The Christian ethic, which protects conjugality, encourages births and prohibits infanticide, contributes to demographic population growth.

Finally, we should point out that more specific events may also have played a decisive role in preventing certain pagan projects. Here is just one example. On 8 November 392, Theodosius the Great published an edict banning all pagan sacrifices and worship. This edict is often seen as the de facto establishment of Christianity as the state religion within the Roman Empire. However, two years later, he had to face a rival, supported by the pagan party. The armies clashed at the Battle of the Cold River in September 394. A defeat for Theodosius could have called his work into question and perhaps even led to a reaction from paganism. However, providentially, the wind blew so hard against the enemy armies that their throwing weapons turned against them. These climatic conditions ensured a total victory for Theodosius. What is interesting is that this fact, reported in detail by Augustine in The City of God, is also confirmed by the pagan poet Claudian.

David Vincent, doctoral student in the history of religions and religious anthropology at the École Pratique des Hautes Études.

Going further:

Paul Veyne, Quand notre monde est devenu chrétien (312-394), Albin Michel, 2007.

More information:

C. Badel and H. Inglebert, Grand atlas de l'Antiquité romaine, Paris, Autrement, 2019.
R. Stark, The Rise of Christianity. Un sociologue revisite l'histoire du christianisme des premiers siècles(French translation: P. Malidor), Excelsis, 2013 (original work published in 1996).