John Locke’s A Letter Concerning Toleration is widely regarded as a foundational text of religious liberty. For centuries, thinkers have praised its clarity, moral confidence, and rejection of the coercive religious politics that prevailed in early modern Europe. On the surface, Locke offers a simple and powerful claim: the state has no authority over the salvation of souls, and therefore it ought not to coerce religious belief or practice.

　　But this framing, so often viewed as self-evident, rests on claims that are highly contestable. Locke’s case is not religiously neutral. His argument becomes far less persuasive once we interrogate his assumptions. Religious freedom is good, but Lockean toleration is too fragile to sustain it.

　　Locke’s argument depends on a sharp division between the civil and the spiritual. The magistrate, he says, is concerned only with outward goods: life, liberty, property. Religion, by contrast, concerns inward belief and the salvation of the soul. Because belief cannot be forced, and because the state has no power over salvation, coercion in religion is both ineffective and illegitimate.

　　The argument is neat, forceful, and compelling on its surface. But it sidesteps rather than engages the thorny issues surrounding religious freedom.

　　Of course, coercion cannot produce genuine faith. This is obvious and had been recognized long before Locke. The deeper issue is that Locke quietly redefines both religion and politics to make his conclusion seem inevitable. Religion becomes primarily inward, a matter of private conviction. The Church becomes something akin to a club, a mere gathering of like-minded individuals. Politics, meanwhile, is reduced to the management of external order.

　　Locke defines the Church as “a voluntary society of men, joining themselves together of their own accord,” thereby sidelining any claim to sacramental or hierarchical authority. Structured worship is treated as irrelevant for the soul and salvation. This flattening of liturgy and sacrament pits inward belief against visible, corporate worship. And when Locke turns to the limits of toleration, the confessional boundaries become unmistakable: “That church can have no right to be tolerated … which is constituted upon such a bottom, that all those who enter into it do thereby ipso facto deliver themselves up to the protection and service of another prince.” The target here is Roman Catholicism, excluded not for principled reasons but due to theological suspicion and political fear.

　　Locke breaks from the way Christian thinkers had treated these topics for centuries. In the classical Christian tradition, religion is not merely inward belief. It is a lived, embodied reality: sacramental, hierarchical, liturgical, and communal. And while politics should protect rights and prevent harms, it also has a pedagogical function. Law shapes habits, forms character, and directs human beings toward the good. The idea that civil authority might have a role in promoting human flourishing was taken for granted.

　　Locke does not so much refute this tradition as ignore it. He argues against the idea that the state can compel the salvation of souls—a position no serious thinker ever held—while leaving largely unaddressed the more sophisticated claim that political authority and religious truth might be ordered toward a common end. When he does offer better reasons for restraining the state, for example by appealing to epistemic humility and the dangers of abuse, he covertly switches from principled to prudential arguments.

　　This leaves Locke’s case in an unstable position. His principled argument depends on contentious assumptions about the nature of religion and politics. His more persuasive arguments are about tendencies and likelihoods. The result is not a bulwark for religious freedom but a contingent framework shaped by the religious anxieties of seventeenth-century England.

　　Religious liberty deserves a better defense. We can find it by looking centuries earlier in Christian history.

　　More than a millennium before Locke, Lucius Caecilius Firmianus Lactantius (ca. 250 – ca. 325 AD) had already articulated a clearer and more coherent rejection of religious coercion. Writing in the early fourth century, during the final phase of Roman persecution and on the cusp of Christianity’s legalization, Lactantius was a rhetorician steeped in classical philosophy. With the support of Emperor Diocletian, he became a professor of rhetoric in Nicomedia, which also facilitated his entrance into the orbit of the imperial elite. We do not know precisely when Lactantius became a Christian, but his conversion almost certainly preceded Diocletian’s persecution of the Church. His career suffered as a result. Saint Jerome, who later praised his literary abilities, attests that Lactantius lived in poverty for years. However, his fortunes reversed when he came to the attention of Constantine, who appointed Lactantius as tutor to his son Crispus. He likely enjoyed imperial favor until the end of his life.

　　Lactantius draws a sharp contrast between two fundamentally different modes of engagement. Violence belongs to the realm of brute compulsion, whereas religion belongs to the realm of reasoned assent.

　　Lactantius’s major work, Divine Institutes, is a bold defense of Christian truth addressed to the Roman elite. He likely began writing it after losing his teaching post in Nicomedia. Although it does not reveal deep knowledge of Holy Scripture or particularly original theology, Divine Institutes was regarded by later Christian writers as a masterwork of Latin style. More importantly, it reveals a broad familiarity with Christian apologetics up to the point of Lactantius in history. What matters for us specifically is his argument for religious freedom. Lactantius is widely regarded as having developed the first principled argument for liberty in matters of conscience. Given his later associations with Constantine, it is likely these ideas influenced the climate of opinion leading up to the Edict of Milan (313), which established toleration for Christianity. Ultimately, Lactantius’s condemnation of coercion in Divine Institutes is both more striking and philosophically serious than Locke’s.

　　Lactantius argues that coercion is inherently opposed to the nature of religion and to the dignity of the human person. “Religion cannot be imposed by force; the matter must be carried on by words rather than by blows.” But he goes even further. Coercion is not merely ineffective; it is irrational and degrading. “For religion is to be defended, not by putting to death, but by dying; not by cruelty, but by patient endurance; not by guilt, but by good faith.”

　　Here Lactantius draws a sharp contrast between two fundamentally different modes of engagement. Violence belongs to the realm of brute compulsion, whereas religion belongs to the realm of reasoned assent. As he puts it, “nothing is so much a matter of free will as religion,” and therefore it cannot be forced upon anyone.

　　This is where a doctrine of human dignity begins to emerge. Lactantius does not use later theological language about the imago Dei, but the logic is unmistakable. Human beings are the kind of creatures who must be addressed through reasons, not coerced through fear. To attempt to produce worship by force is to treat persons as less than rational agents—as inert instruments rather than participants in divine truth.

　　Lactantius does not need to reduce religion to inward belief or politics to the protection of external goods to make his case. He preserves the public reality of religious truth while insisting that it must be embraced freely. Coercion is wrong because faith is too deeply entwined with rational freedom to be compelled.

　　Crucially, Lactantius is no relativist. He writes as a convinced Christian who is eager to defend his faith in public. There is no privatization or interiorization of religion here. Rather, his case for liberty follows from the kind of beings humans are: creatures capable of freely responding to truth.

　　The distinction between forcing belief and acknowledging religious truth is crucial. It allows us to reject compelled conversion and practice without embracing the false idea that religion must be entirely privatized. This provides a far more robust foundation for religious freedom.

　　On this view, coercion in matters of religion is wrong not because the state lacks authority over an essentially private domain, but because it violates human dignity. To compel religious practice is to trample upon the freedom that makes genuine faith possible.

　　Yet religious truth still has an important place in public life. A society may still be shaped by its religious inheritance, its moral vision, and its understanding of the human good. Political institutions and norms always reflect deeper convictions about what is true and what is worthy of pursuit. The United States, for example, has long been influenced by Christian moral assumptions and a widely shared sense of Providential purpose, even while rejecting formal religious establishment.

　　This settlement is much closer to Lactantius than to Locke. It affirms that religion must be free because it is too important to be coerced. It allows religious truth to inform public life, while rejecting the use of force to produce false religious conformity. And it reflects a richer conception of human flourishing than we can find in Locke’s unsatisfying dichotomies.

　　Locke is often credited with discovering, or at least popularizing, the case for religious freedom. In reality, he inherits deeper insights, articulated by thinkers like Lactantius, and reframes them within a set of assumptions that ultimately weaken them. Lactantius’s proto-dignitarian argument is more compelling than Locke’s voluntaristic one. His ideas have a deep foundation in Christian intellectual history and can, even now, serve as a branching point to recover a rich conception of religious freedom, grounded in the nature of the human person. We should return to this earlier understanding rather than draw from Locke’s dry well.