Relatively unknown to many, the Roman Emperor Constantine the Great (r. A.D. 306-337) is arguably one of the most influential people in Christian history. A great conqueror and skilled administrator, he was also a pious Christian visionary who attributed his military victories to divine intervention. In practical terms, he was the head of the Christian church within the Roman Empire for three decades, but he waited to be baptized until his deathbed so that the numerous sins and crimes he had committed as emperor could be forgiven.
Although his mother, Helena, was Christian, Constantine was raised a pagan. His famous conversion occurred on the eve of a battle with Maxentius, his rival for the imperial throne. Constantine saw a sign in the heavens bearing the Greek words “touto nika” (“through this, conquer”).
The sign he saw was not the cross; it had not yet become the symbol of Christianity. The Greek chi-rho monogram (often called the “labarum”) consists of the superimposed Greek letters chi (X) and rho (P), forming the first two letters of the Greek title “Christos,” or “Christ.” Constantine attributed his subsequent victory at the Battle of Milvian Bridge (A.D. 312) to the divine intervention of Christ, who thereby became the patron deity of the Roman Empire.
Constantine thus raised Christianity from a minority faith to a world religion. Previous emperors had sponsored the worship of particular patron gods, so such things weren’t new. However, although Constantine didn’t persecute the pagan religions of his day, he undercut both their authority and their financial foundations by removing state sponsorship from pagan temples and devoting all state religious revenues to Christian clergy and churches. He transformed the nature of Christianity by creating a state-sponsored “Imperial Church.”
Constantine also built three new Christian cities: Jerusalem, Constantinople (“the City of Constantine”) and Rome. Although Constantinople was eventually conquered by the Turks in 1453 and is now the Muslim city of Istanbul in Turkey, it remained the most important center of Christian thought and culture for a thousand years. And Jerusalem and Rome are arguably the two most important Christian cities and pilgrimage destinations today.
Constantine was also indirectly instrumental in creating Christian art, architecture and symbolism. There had been a few Christian symbols associated with believers’ burials, but before Constantine there was no formal Christian art or architecture. When he ordered construction of a number of monumental churches, such as the original St. Peter’s in Rome and the Holy Sepulcher in Jerusalem, he borrowed imperial Roman artistic and architectural forms (e.g., mosaics, statues and basilicas) for his new buildings. Constantine created Christian art forms that persist even today.
Many popular Christian beliefs and practices were institutionalized under Constantine’s supervision. Most important was the cult of the martyrs — the belief that sacred power resided in the tombs and relics of those who had died for the faith.
Though such beliefs had existed among Christians in various forms for over two centuries, by building grand shrines for the veneration of martyrs, Constantine created an official following with pilgrimage and liturgy. Thus, the Holy Sepulcher of Jerusalem, the martyr shrine at the tomb of Jesus, became and remains the greatest pilgrimage site for Christianity, closely followed by the monumental basilicas built by Constantine on the ancient tombs of Peter and Paul in Rome.
Although rebuilt in the 16th century, St. Peter’s Basilica in Rome was originally founded as a martyrium for the bones and relics of Peter, who was martyred there.
Doctrinally, Constantine’s impact on Christianity was equally significant. Although not a theologian of any sort himself, he was an efficient manager and politician who wanted his new state religion properly organized. Thus, he made bishops into state employees and church buildings into state property.
He also realized that theological unity was an important part of political unity and control. Accordingly, he ordered all the bishops of the Empire to convene an assembly at Nicaea (near his new capital at Constantinople) in order to resolve numerous outstanding theological disputes. The result was the ambiguous compromise between Hellenistic philosophy and scripture known as the Nicene Creed (A.D. 325), which has remained a fundamental part of mainstream Christian theology and liturgy ever since.
Constantine facilitated the faith’s transformation into a world religion while, in the process, radically altering its fundamental form and characteristics.
Daniel Peterson founded BYU’s Middle Eastern Texts Initiative, chairs The Interpreter Foundation and blogs on Patheos. William Hamblin is the author of several books on premodern history. They speak only for themselves.