Seventeen hundred years ago, Constantine looked up into the sky, and what he saw changed history. He had a Christian vision — either of the cross or the Chi Rho, the Greek monogram for Christ — and it was accompanied by a message: In this sign, you will conquer. He did. The next day, Constantine defeated his rival Maxentius, and the world was made safe for Christianity.
The Battle of the Milvian Bridge on Oct. 28, 312, by which Constantine became emperor of Rome and its vast empire, shaped the world like few battles in history. His triumph was not the birth of Christianity, but it was the beginning of Christendom. How one views Constantine’s conversion and victory depends very much on how one thinks about Christendom.
Upon arriving in Rome, Constantine did not offer the customary sacrifices to the pagan gods; and he legalized Christianity, which until that point was illegal and periodically subject to violent persecution. From Nero in 64 A.D. to Galerius in 305, 10 different emperors visited the most brutal torture and executions upon Christians, including crucifixion.
Historian Rodney Stark argues that despite — or perhaps because of — this fierce persecution, Christianity grew rapidly in ancient Rome. By his estimate, Christians may have accounted for as much as two-thirds of the population of Rome on the eve of the great battle at the Milvian Bridge. So perhaps it was politically advantageous for Constantine to appeal to Christians. In any case, Constantine had at least the positive witness of his own mother, Helena, who was a devout Christian.
Regardless of motivation, Constantine lavished the considerable resources of imperial power on the Church. He began immediately after his victory, giving a property and villa to the Christian community that became the Lateran complex, where the popes lived for a millennium before transferring to the Vatican. Constantine built the original St. Peter’s over the first-century grave of Peter himself on Vatican hill — confirmed by archaeology in recent decades — as well as the great churches of the Holy Sepulchre in Jerusalem and the Nativity in Bethlehem.
More than building physical churches, Constantine built up the Church itself. Nearly three centuries of clandestine life had impeded the Church’s ability to resolve theological controversies. Constantine summoned the first great council of the Christian Church to formulate orthodox teaching on the divinity of Christ. The council was held in Nicaea, in present day Turkey, not far from what would become the new eponymous capital of Constantinople, when the emperor would move east from Rome. The formula agreed to at Nicaea on the divinity of Jesus — God from God, Light from Light, true God from true God — is still prayed every Sunday at Mass throughout the world.
Nicaea was an imperial acknowledgment of the incompetence of the throne to make theological decisions, and therefore an important step in the liberty of the Church and in developing the concept of a limited state. Constantine asked the Church to clarify its doctrine, rather than making the doctrinal decision himself.
Still, there are those who decry “Constantinianism” (or the “Constantinian captivity” of the Church), arguing that Christianity suffered when Imperial patronage offered the Church the coercive power of the state. It’s a perennial danger, and there is valid historical debate on whether the evangelical expansion of Christianity came at the cost of the purity of doctrine and practice. Stark, for his part, judges that it would have been better if Constantine “had remained a pagan who opposed religious persecution.”
But he did not remain pagan, which from a Christian point of view was at least a blessing for Constantine. The historical judgment is that of a mixed blessing. The Constantinian settlement was better than what preceded it — the age of persecution — and enabled the rise of the Christian Europe and Western civilization. Yet it also brought to the Church the capacity to impose, rather than to propose, the gospel. In the 1,700 years since, the freedom to propose without the power to impose has been an elusive balance.
With the French Revolution, and other developments that opened the door to totalitarianism over the subsequent two centuries, the Church returned to a pre-Constantinian age of brutal persecution in many places. At the same time, the rise of liberal democracy provided space for the Church to live as an evangelizer of culture rather than as a holder of power. Whether the rise of secular fundamentalism will permit that to continue is now a pressing question.
The Church now seeks the liberty to proclaim the gospel, and no longer a Constantinian settlement. The Church is now post-Constantinian, but he remains an indispensable step in her history.
Painting depicting the battle at the Milvian Bridge over the Tiber River in 312.