One thing that united nearly all early freethinkers was their consistent opposition to religious persecution, or to any state interference in religious beliefs and practices that are peaceful. (One notable exception was Thomas Hobbes, who wished the state to control religious practices; but those freethinkers who relied upon Hobbes’s criticisms of the Bible and other matters relating to Christianity typically repudiated his political absolutism.) Most freethinkers from the late seventeenth century through the nineteenth century were tireless advocates not merely of religious toleration but of complete religious freedom, including freedom for Jews and atheists. Additionally, freethinkers in Catholic countries called for freedom for Protestants, while freethinkers in Protestant countries defended freedom for Catholics.

The history of religious persecution in Christendom is complicated, but leading theologians, both Catholic and Protestant (Augustine, Aquinas, Luther, Calvin, etc.), defended it passionately with extensive arguments. Thus if we are to appreciate what the freethinkers were up against and how they crafted their pro-freedom arguments, we must know something about the arguments they sought to overthrow. The purpose of this essay (and the one to follow) is to sketch some of the main pro-persecution arguments. For more details, I recommend the excellent overview by Perez Zagorin, How the Idea of Religious Toleration Came to the West (Princeton University Press, 2005); and the magisterial two-volume work by the Catholic historian Joseph Lecler, Toleration and the Reformation (Longmans, English translation 1960).

While Christians were a small minority in the Roman Empire and sporadic victims of state persecution, some leading Christian apologists defended religious freedom. One of the best was Tertullian (c. 145-225), a lawyer and former pagan who converted to Christianity late in life (and who would himself be condemned as a heretic). Tertullian wrote:

[I]t is a fundamental human right, a privilege of nature, that every man should worship according to his own convictions: one man’s religion neither harms nor helps another man. It is assuredly no part of religion—to which free will and not force should lead us.

A later apologist, Lactantius (c. 240-320), argued that religious beliefs cannot be meritorious unless they are accepted freely—a theme that would reverberate for many centuries in the arguments for toleration.

If you wish to defend religion by bloodshed, and by tortures, and by guilt, it will no longer be defended, but will be polluted and profaned. For nothing is so much a matter of free-will as religion; in which, if the mind of the worshipper is disinclined to it, religion is at once taken away, and ceases to exist.

Lactantius dismissed a rationale for persecution that, ironically, would later be used by Augustine to defend persecution by Christians. Perhaps the beneficiaries of persecution are the victims themselves. Perhaps Christians benefit in the long run when they are compelled to sacrifice to the pagan gods. The response of Lactantius to this “for their own good” argument was brief but suggestive: “that is not a kindness which is done to one who refuses it.” True concern for the welfare of others is never manifested in violence or threats of violence.

Lactantius considered another justification for Roman persecution: that it served the pagan gods who rightfully demanded sacrifices as tokens of loyalty, gratitude, and esteem. (Again, this argument, appropriately modified, would later become a mainstay of Christian persecutors, especially Calvinists.) According to Lactantius, however, “that is not a sacrifice which is extorted from a person against his will.” Unless a sacrifice is offered “spontaneously” and “from the soul,” it is nothing more than a “curse” extracted “by injuries, by prison, by tortures.”

Perhaps the most interesting argument by Lactantius is one that would be invoked repeatedly by later freethinkers. Suppose a god really does demand worship by violent means. Any such god, Lactantius retorted, would be unworthy of our worship. Cruel gods “are doubtless worthy of the detestation of men, since libations are made to them with tears, with groaning, and with blood flowing from all the limbs.”

In 313 the Edict of Milan (issued jointly by Constantine and Licinius) established religious liberty as a fundamental principle of public law. Before long, however, the Emperor Constantine was bestowing special favors on the Christian Church. His Christian successors continued this policy until Theodosius revoked the Edict of Milan during his despotic reign (379-95). This emperor established orthodox Christianity as the official religion, outlawed pagan worship and rituals, and decreed severe penalties for heresy.

Thus did a religion born in opposition to the state become its friend and ally. As the classical liberal and Catholic historian Lord Acton put it: “Christianity, which in earlier times had addressed itself to the masses, and relied on the principle of liberty, now made its appeal to the rulers, and threw its mighty influence into the scale of authority.”

Since the hare is more likely than the hound to oppose bloodsports, it is perhaps understandable why the number of Christian defenders of religious freedom declined precipitously after Christians gained control of the reins of state power. Indeed, it was left to the perverse genius of St. Augustine (354-430) to develop the first systematic defense of religious persecution in the history of western civilization. Augustine called his approach “righteous persecution” because it justified persecution for the righteous cause of saving people from the eternal torments of hell. This was essentially a variant of the “for their own good” argument that Lactantius had rebutted previously, and it would remain a powerful and popular argument for many centuries.

Augustine started out as an eloquent defender of religious toleration, but he changed his mind after becoming embroiled in a bitter and sometimes violent conflict (in North Africa) with a large group of Christian schismatics known as Donatists. Augustine’s initial case for toleration was based largely on the fact that beliefs per se cannot be compelled. “No one can or ought to be constrained to believe,” according to the early Augustine. The mind cannot be forced to believe a doctrine; only arguments, evidence, or internal events (such as a flash of inspiration) can cause us to believe something, so coercion is useless in matters of religion. This argument, which became a standard refrain in later arguments for toleration—we find it in the Levellers and in Locke, for example—might seem impossible to overcome, but Augustine was an ingenious fellow. After converting to a champion of persecution, Augustine replied to his own early argument by pointing out that empirical evidence did not support the theoretical claim that coercion is impotent in matters of belief. After all, there were many instances of heretics who had been “brought over to the Catholic unity by fear.”

Clearly, persecution had worked in those cases, but how? Augustine still denied that beliefs per se can be compelled, at least directly, but the threat of force can break “the heavy chains of inveterate custom.” Some heretics were “too listless, or conceited, or sluggish, to take pains to examine Catholic truth.” Others feared reprisals from fellow heretics. Others were raised as heretics and never knew any better. Others planned to embrace orthodoxy eventually but were afflicted with procrastination. In such cases, according to Augustine, persecution, though unable to compel belief, can and often does change the heretic’s mental attitude by breaking the bonds of bad habits, indifference, and sloth. Thus even if coercion cannot impart truth, it can prepare the heretic to hear and receive the truth. The fear of punishment cannot change a person’s beliefs directly, but it can influence them indirectly by softening up the heretic, so to speak.

But even if we grant that coercion can affect beliefs, why should Christians use force or the threat of force against heretics and others who do not subscribe to the tenets of orthodox Christianity? Here Augustine presented the interesting hypothetical of a house which we know “with absolute certainty” is about to collapse and kill everyone inside. If the inhabitants ignore our repeated warnings to get out, then what should we do? Should we rescue them against their wills and then reason with them afterwards? Yes, said Augustine: “I think that if we abstained from doing it, we should well deserve the charge of cruelty.” But suppose that as we undertake our forcible rescue all occupants except one kill themselves by leaping out of high windows? Should we blame ourselves for those deaths? No, said Augustine: “we should console ourselves in our grief for the loss of the rest by the thoughts of the one [who was rescued]; and we should not allow all to perish without a single rescue, in the fear lest the remainder should destroy themselves.”

Having laid the altruistic foundation of his argument, Augustine proceeded to its predictable and logical conclusion. If “true reason and benevolence” demand that we forcibly secure the safety of people “for the brief space of their life on earth,” then it certainly follows that we should also compel them “in order that men may attain eternal life and escape eternal punishment.” Hence the righteous persecution of heretics is nothing less than a “work of mercy to which we ought to apply ourselves.” We should note, however, that Augustine—unlike Aquinas, Calvin, and many later defenders of persecution—opposed putting heretics to death. After all, there can be no hope of saving the soul of a dead heretic.

A fascinating feature of Augustine’s defense of righteous persecution is its broad application to areas other than religion. The “for their own good” argument is a common justification today for many victimless crime laws in the United States and other countries. The most egregious examples, of course, appear in the rationales for drug laws. Years ago I discussed this matter in considerable detail in my article “The Righteous Persecution of Drug Consumers” (Chapter 12 of Atheism, Ayn Rand, and Other Heresies, 1990). The similarities between the justifications given by modern drug inquisitors and Augustine’s arguments for righteous persecution are striking in almost every particular. Here is just one example from my earlier discussion.

Heretics, Augustine believed, imperil their “spiritual health”; they are destined to suffer the torments of hell. Thus, those who truly “love their neighbor” will recognize their “duty” to compel these “wandering sheep.” Righteous persecutors are like physicians who try to help a “raving madman,” for heretics “commit murder on their own persons.” When motivated by love, persecutors cannot do evil: “Love and you cannot but do well.”

In true Augustinian fashion, the modern drug inquisitor seeks to “heal” wayward drug users who “commit murder on their own persons.” Indeed, Augustine’s defense of righteous persecution anticipates virtually every argument used by drug inquisitors.

For example, our modern inquisitors claim that drug consumers are slaves to evil habits and so require coercive intervention for their own good. Augustine, too, warned against the “fetters” of sinful habits which have the “strength of iron chains.” These evil habits (“a disease of the mind”) become a “necessity,” forming a “chain” which holds the victim [the heretic] “in the duress of servitude.”

I took this detour to point out that contemporary freethinkers should not be smug about their supposed superiority to early Christians who defended persecution. The particulars may differ, but the essential form of Augustine’s argument remains in full force among those defenders of drug laws, compulsory medical care, and the many other instances in which a government compels people “for their own good.” It took many centuries for Augustine’s argument to be decisively refuted, and that required a theory of individual rights of the sort that libertarians now defend. This is a lesson that all freethinkers should keep in mind.