Religious and civil authority were once unified—pagan gods and political rulers were one, church and state were indistinguishable, and the individual’s religious allegiance was bound up with his political allegiance. Political rulers asserted authority over the spiritual decisions of their subjects, frequently applying the coercive power of civil government to ensure orthodox belief and practice. Religious toleration, if it existed at all, was a matter of expediency rather than principle. 

The coming of Christianity and the fundamental distinction it drew between spiritual and civil power brought recognition of a separate spiritual authority which sought to check the unrestrained power of the state. Christianity severs the individual’s religious obligation from his political obligation, as expressed in Jesus’ injunction to “give back to Caesar what is Caesar’s, and give to God what is God’s.” It proclaims that a person’s supreme duty is to God, who transcends all temporal and political orders, thereby placing spiritual matters fundamentally outside the sphere of civil command. 

Religious Freedom under Constantine

The church-state question was profoundly complicated by the conversion of Emperor  Constantine in the fourth century and the subsequent adoption of Christianity as the official religion of the Roman empire. The alliance of Christianity with the state and its coercive power posed new questions: Does this alliance somehow re-legitimize the claim of the emperor to supremacy in all things, including matters of religion? To what extent, if any, should the state’s coercive power be applied to convert unbelievers and to correct heretics? These questions would vex the church for the next millennium. 

Once Constantine took the throne, he realized that it was neither possible nor desirable to eliminate Christianity, so he sought a solution that would reconcile the empire’s need for religious validation with the Christians’ refusal to worship any other deity. The Constantinian solution was to secure Christian support of the empire by creating a polity in which Christians and pagans could participate on equal terms under an umbrella of general monotheism.

The Edict of Milan

The centerpiece of Constantine’s religious policy was the Edict of Milan, issued with his co-emperor Licinius in 313, which proclaimed religious freedom in the Roman Empire. The edict was remarkable in that it recognized that religious devotion should not be coerced. The emperors granted “to the Christians and others full authority to observe that religion which each prefer[s],” because no one should be denied “the opportunity to give his heart to the observance of the Christian religion, [or to] that religion which he should think best for himself.”

Religious observance may occur “freely and openly, without molestation” so that “each one may have the free opportunity to worship as he pleases.” Historian H. A. Drake explains that these features made the edict more radical and far-reaching than a simple grant of toleration to Christians: 

The edict constitutes a landmark in the evolution of Western thought—not because it gives legal standing to Christianity, which it does, but because it is  the first official government document in the Western world to recognize the  principle of freedom of belief.

The Influence of Lactantius

Constantine’s grant of religious freedom in the Edict of Milan reflected the influence of Lactantius, a Christian scholar and rhetorician who had fled to the West during the persecution ordered by Diocletian in 303. He subsequently joined the court of Constantine and became tutor to his eldest son, Crispus. Between 305 and 310, Lactantius wrote the Divine Institutes to counter the arguments of Porphyry, a Greek philosopher in the court of Diocletian who had provided a philosophical justification for the persecution of Christians. By arguing for why religion of any sort cannot be coerced, the Divine Institutes provided the underpinnings of Constantine’s religious policy. Michel Perrin calls book five of the Divine Institutes a “manifesto for the liberty of religion.” 

Few in history have voiced the argument for religious freedom more eloquently than  Lactantius. He is the first Western thinker to present a comprehensive argument for religious freedom rooted not in secular notions of toleration but in the nature of God and of authentic religious belief. The object of true religion is a loving God, he argued, and thus by its very nature religion is not something that can be coerced. “For nothing is so much a matter of free will as religion,” he wrote, “in which, if the mind of the worshipper is disinclined to it, religion is at once taken away, and ceases to exist.” Those who use force, Lactantius wrote, “neither know themselves nor their gods.” 

Lactantius insisted that genuine religious devotion must be voluntary. “There is no need of force and injury,” he wrote, “because religion cannot be forced. It is a matter that must be managed by words rather than blows, so that it may be voluntary.” Force and violence only defile religion and produce hypocrisy.

His arguments showed Roman persecutors that Christianity—not pagan religion—was committed to rational dialogue which had been the hallmark of classical thought. “Let them  imitate us in setting forth the system of the whole matter,” Lactantius wrote, “for we do not entice, as they say; but we teach, we prove, we show.” 

The Birth of Religious Freedom

Although in many ways a minor historical character, Lactantius was the first to conceive of a  comprehensive and principled theological argument for religious freedom. The immediate influence of his thinking on Constantine’s religious policy resulted in a remarkably novel commitment by the state to religious freedom, something heretofore unrealized in his day.

We should not be surprised to learn, therefore, that prominent sixteenth and seventeenth-century advocates for religious freedom frequently turned to Lactantius as a source for their ideas. 

Editor’s note: This article is adapted from Set Free: Restoring Religious Freedom for All (Abilene Christian University Press, 2019). Save $10, while supplies last! Order here.