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Constantine’s Foil

How Peace in Rome Led to Persecution in Persia

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Professor, Gordon-Conwell Theological Seminary

ABSTRACT: Constantine’s conversion to Christianity in the early fourth century brought an end to state-sponsored persecution in the Roman empire. Around the same time, however, the relatively peaceful Persian empire turned violently upon the church in its lands. Though the accurate number of martyrs remains difficult to assess, the most conservative estimates place the death toll in the Great Persian Persecution (339–379) far higher — even ten times higher — than the death toll in the worst Roman persecution. In response to such widespread assaults, many Persian Christians fled if they could. Many others, either unable or unwilling to flee, took courage from stories of faithful sufferers and stood firm. Today, their testimonies still give fresh courage to those who suffer for Christ.

When Western Protestants think of the persecution of early Christians, we often imagine believers being thrown to the lions in the Roman Colosseum. According to the story as we learned it in Sunday school and elsewhere, Christians were ruthlessly persecuted for their faith for three centuries, until Constantine’s dramatic conversion around the year 312 brought about a sea change in the Roman empire’s attitude toward Christianity.

This Sunday school version of the story, while not wrong, is both misleading and incomplete. It is misleading because it gives the impression that persecution in the Roman empire was continuous, when in fact it was sporadic, varying from nonexistent to severe, depending on where and when one lived. This story is also incomplete because it does not even acknowledge by far the worst persecution of Christians in the ancient world, the Great Persian Persecution instigated by Shah Shapur II in 339.1 Many Western Christians are not aware that Christianity quickly took root in Persia (approximately modern-day Iran and Iraq) in ancient times.2 A look at the differing fortunes of Christians in the Roman and Persian empires, as well as the ways they responded to persecution, yields important lessons for believers today.

Two Great Persecutions Compared

Persecution of Christians in the Roman empire was generally local in character, confined to a region based on the personal antipathy of the governor toward the faith. But there were two major periods of widespread persecution, encompassing most regions of the empire at the same time. These were a persecution under emperors Decius and Valerian in the 250s, and the Great Persecution under Emperor Diocletian, which began in 303 and lasted a couple of years in the western part of the empire and a couple of decades in the eastern part. It was during this Great Persecution that Constantine became a Christian and gained control over the entire Roman empire.

By carefully counting the martyr lists in given regions at given times, modern scholars can gain a general picture of the severity of the persecution and then extrapolate to arrive at guesses of how many believers were killed in total. An estimate that has gained scholarly acceptance is perhaps 3,000–3,500 deaths in all, of which maybe 500 happened in the west and 2,500–3,000 in the eastern parts of the empire.3 When we consider that in the early fourth century, the population of the Roman empire was between 60 and 75 million people, of whom perhaps 10 percent (or about 6–7 million) were Christians, we can see that the total death toll was relatively small.

In contrast, the Great Persian Persecution is traditionally regarded as having lasted forty years, from 339 until Shapur’s death in 379. In actuality, it was frightfully intense for a couple of decades and then ebbed and flowed until the early fifth century, well beyond the life span of Shapur himself. Estimating deaths from this persecution is much harder than in the case of Diocletian’s, but one of the earliest reports we have is sobering.

The church historian Sozomen, writing about 440, declares, “I shall simply state that the number of men and women whose names have been ascertained, and who were martyred at this period, have been computed to be sixteen thousand; while the multitude outside of these is beyond enumeration.”4 This statement, even if exaggerated, points to a huge death toll. Modern estimates have varied from as many as the eye-popping figure of 190,0005 down to a more “modest” figure of 35,000.6 Even the conservative estimate is ten times the number of Christians martyred in the Great Roman Persecution, although the Persian empire’s population (perhaps 18–35 million) was less than half that of the Roman, with a much smaller Christian population as well. By any estimate, the loss of life in the Great Persian Persecution was immeasurably greater than the death toll of the Great Roman Persecution a few decades earlier.

“The loss of life in the Great Persian Persecution was immeasurably greater than the death toll of the Great Roman Persecution.”

This staggering death toll is all the more surprising when we consider that prior to the fourth century, there had been no significant persecution of Christians in the Persian empire at all. Indeed, early in the fourth century, just as the Roman empire shifted from persecuting Christians (in varying degrees in different places and times) to favoring our faith, the Persian empire changed from basically ignoring Christians to unleashing a savage persecution on them. How did such a shocking change come about? To answer this question, we will need a brief overview of early Christianity in the Persian empire.

Treatment of Christians in the Persian Empire

The early Christian period took place during the long reigns of two great Persian dynasties: the Parthians, who ruled from 247 BC until AD 224, and the Sassanids, who reigned from 224 until they were conquered by the Arabs in 651. The Parthian period was one of relative peace in Persia, and there was essentially no state action against Christians, for several possible reasons.

First, the Parthian regime was benign and decentralized, with a great deal of provincial autonomy. There was little persecution of anyone for any reason. Second, the Romans were the major menace to Persia, and it was common for Persian rulers to take the opposite position on any matter that was important to Rome. Since the Romans were suspicious of their Christian population, the Persians tended to welcome them or at least to leave them alone. Third was the fact that Zoroastrianism, the dominant religion in Persia, was much closer to the Christian faith than Roman polytheism. Zoroastrianism was a dualistic religion focused on the conflict between good and evil, and there were superficial resemblances with Christianity, such as a belief in a coming messiah and judgment after death. As a result, Christians did not stand out in Persian society nearly to the degree they did in pagan Roman society.

The political situation of Persia changed dramatically in the early third century. Significant invasions from Roman forces fueled a popular rebellion against the peaceful Parthian dynasty. A much more authoritarian regime, the Sassanids, gained popular favor on a platform of keeping Persia safe from the Romans, and in 224, they took control. The Sassanids were strict Zoroastrians and made that religion the national faith of Persia.

This time period also saw the rise of Manichaeism, another form of dualism that was directly in competition with Zoroastrianism. Its prophet, Mani, combined many features of Zoroastrianism with some specifically Christian language (he even called himself a disciple of Jesus Christ), and Manichaeism spread like wildfire in Persia and beyond. It was clearly a threat to the national religion, and in the 270s Mani was executed by crucifixion. To the Sassanid rulers, Christianity and Manichaeism looked the same,7 and there was some minor persecution of Christians from 276 to 293 because they were incorrectly thought to be Manichaeans. This was the first time Christians were targeted for ill-treatment in the Persian empire, and while the suffering was mild, it is noteworthy that it came about mainly because of mistaken identity.8

Shapur’s Persecution of Christians

The dawn of the fourth century saw Persia facing increased threats not only from the Romans (who captured most of northern Mesopotamia), but also from the Arabs and other wandering groups who attacked at the same time. When Shah Shapur II was born in 309, the empire seemed on the verge of collapse, but while still a teenager he steeled the Persian people to retake their homeland from invaders again.

Sometime before 325, the now-Christian Roman emperor Constantine wrote Shapur a letter, in which he encouraged the young shah to embrace Christianity.9 Constantine pointed out the presence of many Christians in Persia and urged Shapur to treat them well: “Now, because your power is great, I commend these persons to your protection; because your piety is eminent, I commit them to your care. Cherish them with your wonted humanity and kindness; for by this proof of faith you will secure an immeasurable benefit both to yourself and us.”10 In the process of making these suggestions, Constantine inadvertently called the attention of Shapur’s advisers both to the presence of Christians in their midst and to the fact that Rome now favored followers of the new religion.

In the 330s, with the Roman world solidly in his control and largely Christian, Constantine prepared for another Roman attack on Persia, but he fell ill and died in 337. Shapur immediately counterattacked in an attempt to retake the city of Nisibis (in extreme southeastern Turkey today), which the Romans had taken from Persia some four decades earlier. Shapur’s attack failed, and he blamed the defeat on the Christians in Nisibis, who he claimed had aided the Roman army. Back in the Persian capital, Seleucia-Ctesiphon (on the lower Tigris River near current-day Baghdad), rumors swirled that the Christian bishop of the city, Simon, was providing military intelligence to the Romans. Zoroastrian religious officials spread the rumors to stoke fires of animosity toward Christians, and in 339, Shapur began his massive crackdown on Christians.

The shah began by doubling the taxes on Christians and ordering Bishop Simon to collect. When Simon predictably refused,11 Shapur ordered the destruction of churches and the execution of bishops who refused to take part in the national worship of the sun. The shah personally offered Simon gifts if he would take part in the prescribed worship, but threatened to kill all Christians if he refused. Simon remained obstinate and was thrown into prison to reconsider. Finally, Shapur forced Simon to watch the execution of more than a hundred other Christian clergy before he too was beheaded.12 For at least the next twenty years, the Persians killed Christians throughout their empire. Most of the time, they identified church leaders and singled them out for execution. At other times, the Persians targeted Christians who had converted from Zoroastrianism — that is, native Persian converts, as opposed to Jews or Syrian foreigners who had become Christian. Occasionally they resorted simply to the indiscriminate massacre of Christian populations.

In the 360s, Shapur again had to face a Roman invasion, this one from Constantine’s nephew Julian the Apostate, who had thrown off his Christian upbringing and who had visions not only of restoring the glory of pagan Rome but also of becoming himself a new Alexander the Great. Julian advanced almost to Seleucia-Ctesiphon before being driven back and ultimately killed in battle in 363. Shapur showed no mercy to the defeated Romans; he demanded and received back all the Persian territory that had been taken before his birth. At this point, the shah may have slackened the persecution of Christians within his realm, but even after his death, the new Zoroastrian suspicion that Christians were Roman spies did not completely die down, and persecution continued sporadically.

Finally, in 409 Shah Yazdegerd I issued a decree of toleration. A council held in the capital in 410 praised Yazdegerd for his action and declared the bishop of Seleucia-Ctesiphon, Isaac, to be the head (“catholicos”) of the Persian church. But unlike the situation in the Roman world, this edict of toleration would bring no lasting political favor toward Christianity, and the Persian church would live with an uncertain relationship to the state for the rest of its history.13

Persian Christian Responses to Persecution

The responses of Persian Christians to the Great Persecution are especially noteworthy in three ways, all of which stand in partial contrast to the earlier responses of Roman Christians to their Great Persecution.

First, in Persia, we have no evidence of the subversive maneuvering that seems to have been common farther west. In the Roman empire, we have stories of Christians who, when imperial officials came for their copies of the Scriptures, either gave the officials the runaround by sending them to one church member after another (in the hope that they would give up before finding any copies), or handed over heretical writings rather than the Scriptures, or in one case even turned in a medical textbook in the hope that the official either couldn’t read or wouldn’t care as long as he could show some confiscated writing for his efforts.14 No such accounts survive from Persia. Perhaps the Persian Christians were just as cunning as many Roman believers, and we happen to not possess the evidence. Or perhaps they were genuinely more heroic.

Second, we have a good deal of evidence of Persian Christians “voting with their feet” — attempting to read the political situation and migrating to areas they thought would give them more freedom to practice their faith. Such migration actually began even before the Great Persian Persecution. In the third century, when Rome was suspicious of Christians and Persia was more tolerant of them, the Persian church moved its center of operations from Edessa (on the disputed border between the empires) east to Nisibis and even southeast to the Persian capital Seleucia-Ctesiphon. Then as the axe fell on Persian Christians in the fourth century, a number of them — including their most famous theologian/poet Ephrem the Syrian — moved back to the Roman orbit in response to the new political reality.

Even more strikingly, at the height of the Persian Persecution in 345, a group of some four hundred Persian Christians arrived on India’s Malabar Coast (southwestern India) to join the Christians who were already there. These newcomers seem to have been fleeing the Great Persian Persecution, and their presence in India forged bonds between Indian and Persian Christianity that would remain, to some degree, until the present day.15

Third, Persian Christians steeled themselves for resistance and suffering. We have a series of homilies from the pen of a fourth-century Persian writer named Aphrahat, and part of his purpose in preaching these sermons was clearly to encourage Christians who could not escape the hand of Shapur by fleeing Persia. Aphrahat recounted numerous examples of persecution from the Bible, emphasizing that God was still present with his people in the midst of their trials.16 Then surprisingly, he added to these biblical exemplars of heroic suffering for the faith a much more recent one:

Concerning our brethren who are in the West, in the days of Diocletian there came great affliction and persecution to the whole Church of God, which was in all their region. The Churches were overthrown and uprooted, and many confessors and martyrs made confession. And [the Lord] turned in mercy to them after they were persecuted.17

Aphrahat concluded that the church in Persia also had the opportunity to make confession in the midst of its own persecution.

This homily shows a remarkable degree of hope in the midst of a terrible ordeal, but it also demonstrates an equally noteworthy sense of solidarity with Christians in the Roman world. This solidarity is all the more striking since Rome and Persia were mortal enemies at the time, and since few Western Christians then were aware of their sisters and brothers in the Persian world.

Remembering the Persecuted

Most of us know that the Romans dramatically changed their attitude toward Christianity in the early fourth century, but in this essay we have seen that Persia did so as well — in the opposite direction. Shapur’s name is not as well-known as Diocletian’s or Constantine’s, but perhaps it should be. In fact, the very conversion of the Roman empire that brought persecution to an end in the West was one of the main reasons for the persecution of Christians farther east.

The situation of believers was drastically different at various times, and even in different places at the same time. Believers had to make their way through life in the midst of constant uncertainty about the attitude of the government and the surrounding society to their faith. When they could, they sought out regimes that were friendly to Christianity. When necessary, they steeled themselves to face persecution by remembering the sufferings of God’s people in Scripture and Christian history elsewhere. Church-state relationships have always been complicated, changing, and replete with challenges.

As a result, it is important for us not to use too narrow a lens as we examine the impact of political and social forces on Christians. In the fourth century, what was proclaimed in the West to be a miracle and a spectacular blessing led fairly directly to untold suffering for Christians outside the Roman world. Yet, so far as we know, Christians in Persia harbored no ill will toward their newly blessed Roman brothers and sisters. Instead, the Persian believers leaned on the Romans’ example of endurance in suffering as they bore down to suffer in their turn.

“There may come a time when Western Christians must again suffer greatly under persecution.”

Today as well, most of the Christians who suffer grievously for the faith do so in eastern and southern lands (especially the Middle East and eastern Africa), not in western ones. Today the persecutors are not the Persians, but often the Muslim Arabs who conquered Persia (and all of western Asia and northern Africa) in the seventh and eighth centuries. But the Christians who suffer persecution today have a long history of bearing it with patience and as much grace as possible. They have seen this before, and their history is full of stories that help to sustain them.

Meanwhile, we in the West suffer very little, if at all, for the faith. Will we learn the stories of our brothers and sisters in the East, both then and now? Will we stand against the great injustices done to them by societies opposed to the gospel, even as we stand against the much smaller injuries perhaps done against us by our societies that have largely turned their back on Christ? After all, there may come a time when Western Christians must again suffer greatly under persecution, and we will need to be ready.


  1. For more information on the Persian Christian history described in this essay, see the following three books: Donald Fairbairn, The Global Church — The First Eight Centuries: From Pentecost through the Rise of Islam (Grand Rapids: Zondervan Academic, 2021); Christoph Baumer, The Church of the East: An Illustrated History of Assyrian Christianity, new ed. (New York: I.B. Tauris, 2016); Samuel Hugh Moffett, A History of Christianity in Asia, Volume 1: Beginnings to 1500, rev. ed. (Maryknoll, NY: Orbis, 1998). In this essay, I will cite the pages of The Global Church where one may find more detail on the subjects I discuss, and the references in that book will further direct the reader to Baumer, Moffett, and other sources. 

  2. Christianity was well established in western Persia (approximately eastern Turkey and northern Syria today) by the middle of the second century, and possibly even in the first. During the third and fourth centuries, the church spread much deeper into Persia. See Fairbairn, The Global Church, 41–45, and the sources cited there. 

  3. See William H.C. Frend, Martyrdom and Persecution in the Early Church: A Study of a Conflict from the Maccabees to Donatus (Oxford: Basil Blackwell, 1965), 536–37. 

  4. Sozomen, Ecclesiastical History 2.14. See The Nicene and Post-Nicene Fathers, Series 2, ed. Philip Schaff, 14 vols. (1886–1889; repr., Peabody, MA: Hendrickson, 1994), 2:267. (Henceforth I will abbreviate this series as NPNF 2.) 

  5. Louis C. Casartelli, “Sassanians,” in Hastings Encyclopaedia of Religion and Ethics, ed. James Hastings, vol. 11 (New York: Charles Scribner’s Sons, 1920), 203. This figure is repeated, although not necessarily endorsed, in Moffett, A History of Christianity in Asia, 145. 

  6. James R. Russell, “CHRISTIANITY i. In Pre-Islamic Persia: Literary Sources,” in Encyclopædia Iranica V/5 (Costa Mesa, CA: Mazda, 1991), 327–28; available online at http://www.iranicaonline.org/articles/christianity-i

  7. In different regions of the ancient world, Manichaeism was characterized as a Christian heresy, as an acceptable form of Christianity, or as a Zoroastrian or Buddhist heresy. 

  8. For more on Christianity in the Persian empire, see Fairbairn, The Global Church, 62–63, and the sources cited there. 

  9. Preserved in Eusebius, Ecclesiastical History 94.9–13 (NPNF 2 1:543–44). Also in Theodoret, Church History 1.24 (NPNF 2 3:59–60). 

  10. Eusebius, Ecclesiastical History 4.13 (NPNF 2 1:544). Also in Theodoret, Church History 1.24 (NPNF 2 3:60). 

  11. Sozomen notes that the Christians had voluntarily embraced poverty, which presumably means it would have done the empire no good to tax them double. See Sozomen, Church History 2.9 (NPNF 2 2:264). 

  12. Sozomen, Church History 2.9–10 (NPNF 2 2.264–66). 

  13. For more on the Great Persian Persecution, see Fairbairn, The Global Church, 156–59, and the sources cited there. 

  14. See Fairbairn, The Global Church, 148–49, and the sources cited there. 

  15. On the possible presence of Christians in India prior to 345, see Fairbairn, The Global Church, 42–45, 63–65, and the sources cited there. On the delegation of Persian Christians arriving in 345, see 164–67. 

  16. Aphrahat, Demonstration 21.1–23 (NPNF 2 13:392–401). 

  17. Aphrahat, Demonstration 21.23 (NPNF 2 13:401). 

is the Robert E. Cooley Professor of Early Christianity at Gordon-Conwell Theological Seminary. His books include Life in the Trinity, The Story of Creeds and Confessions, and The Global Church — The First Eight Centuries.