The Evolution of Religious Tolerance in the Western World

Few ideas in Western history have been as hard-won as the right to worship freely. What we now consider a basic human right was, for centuries, a radical and dangerous proposition. Religious tolerance in the Western world did not emerge from goodwill alone – it was forged through centuries of war, persecution, philosophical argument, and political compromise. Tracing its evolution from the Roman Empire through the Enlightenment reveals not a smooth arc of progress, but a turbulent, back-and-forth struggle that ultimately transformed how Western societies understand the relationship between faith, power, and individual freedom.

Rome’s pragmatic pluralism 🔗

The Roman Empire is often cited as an early model of religious coexistence, but it is important to understand what that coexistence actually looked like. Rome granted religious toleration to its subject peoples as long as they also honored Roman gods. This was not tolerance rooted in principle – it was tolerance rooted in political calculation. The empire was vast, multi-ethnic, and multi-religious, and forcing uniformity on conquered peoples would have been impractical and destabilizing.

Roman religion was practical and contractual, based on reciprocal obligations between humans and the divine. Because Romans had never been required to worship just one deity, the question of religious tolerance did not arise in the way it would for monotheistic systems. Multiple gods, multiple cults, and imported religions from across the empire coexisted – albeit uneasily at times.

The religions that Rome struggled most to accommodate were monotheistic ones: Judaism and Christianity. Because these religions believed in just one god, their followers refused to make offerings to Roman gods or participate in Roman religious festivals, which Rome considered a matter of showing loyalty. This refusal was not merely a theological difference – it was read as a political threat.

Constantine and the Edict of Milan 🔗

The pivotal shift came in 313 CE, when Emperor Constantine issued the Edict of Milan, granting religious tolerance to Christians. The edict proclaimed that every person was free to follow the religion of their choice, and under Constantine, Christianity rapidly became the dominant religion. By 380 CE, Emperor Theodosius had made it Rome’s official state religion.

This transformation had a paradoxical consequence. In the fourth century, Christianity became the official religion of the Roman Empire and the state became an active participant in church matters. Religious pluralism, once fundamental to the empire’s character, was brought to an end. The religion that had once been persecuted became the persecutor. Heresy – disagreement with official church doctrine – was now not just a spiritual failing but a legal crime. The first executions for heresy followed within the same century.

The medieval turn toward intolerance 🔗

Through the medieval period, the Catholic Church consolidated its authority over religious life in the West, and dissent was increasingly met with force. The church launched a crusade against the Cathars in 1209, effectively exterminating them. The burning of heretics was mandated in France in 1270, and in England in 1401. Heresy was not just seen as personal sin – it was understood as a contagion that could endanger the salvation of an entire community, and so suppressing it was framed as an act of mercy toward society.

The tumultuous events of the European religious civil wars in the 16th and 17th centuries significantly influenced the contemporary conception of tolerance. It was precisely the failure of violent religious enforcement – the bloodshed, the instability, the unresolvable conflicts – that eventually pushed thinkers and rulers toward a different approach.

The Reformation fractures Christian unity 🔗

The Protestant Reformation, launched when Martin Luther published his Ninety-Five Theses in 1517, shattered the Catholic Church’s near-monopoly on religious life in Europe. But the Reformation did not immediately produce religious tolerance. Although Luther was himself a heretic in the opinion of the Catholic Church, Luther had no interest in religious toleration. For Luther, as for his medieval Catholic predecessors, religious unity presupposed that Christian society and the church must be coterminous.

What the Reformation did produce was fragmentation – dozens of competing Protestant sects alongside a reformed but embattled Catholicism. This fragmentation made religious warfare inevitable. France alone experienced eight civil wars between Catholics and Protestants between 1562 and 1598. The Thirty Years’ War (1618-1648) devastated much of Central Europe. The Peace of Westphalia in 1648 organized European laws to allow Christian minorities to exist, marking a grudging but significant shift toward the idea that pluralism could be a workable political arrangement.

The Edict of Nantes: a fragile breakthrough 🔗

Before Westphalia, France arrived at its own landmark moment of managed coexistence. The Edict of Nantes, promulgated at Nantes in Brittany on April 13, 1598, by Henry IV of France, granted a large measure of religious liberty to his Protestant subjects, the Huguenots. It was one of the first decrees of religious tolerance in early modern Europe, and its significance is hard to overstate.

Henry IV’s France had been racked by decades of brutal conflict. At least seven thousand Huguenots were killed by royal forces in the St. Bartholomew’s Day Massacre of August 1572 alone. Henry, a former Protestant who had converted to Catholicism to secure the throne, understood that neither side could simply exterminate the other. The Edict was a pragmatic peace.

France officially proclaimed for the first time that people were free to profess the religion of their choice, although Catholicism would remain the religion of the kingdom. In practical terms, the edict granted Huguenots the right to worship in designated towns, to hold public office, to attend university, and to have their legal disputes heard in a special mixed court. It also separated civil unity from religious uniformity – a conceptually revolutionary move. The edict treated some Protestants for the first time as more than mere schismatics and heretics, and opened a path for secularism and tolerance.

The revocation and its consequences 🔗

The Edict’s fragility became clear in 1685, when King Louis XIV reversed it entirely. On October 18, 1685, Louis XIV formally revoked the Edict of Nantes and deprived French Protestants of all religious and civil liberties. Within a few years, more than 400,000 persecuted Huguenots emigrated – to England, Prussia, Holland, and America – depriving France of its most industrious commercial class.

The revocation had lasting consequences beyond France’s borders. It shocked Protestant Europe and helped galvanize a generation of thinkers who argued that the alliance of church and state was not only morally wrong but politically destructive. Among them was John Locke, who was living in Holland in 1685 when the revocation occurred and was moved to formalize his arguments for toleration.

The Enlightenment: toleration as a philosophical principle 🔗

The Enlightenment, roughly spanning the late 17th to the 18th century, transformed religious tolerance from a political compromise into a philosophical principle. Philosophers such as Spinoza, Bayle, and Locke presented influential theories advocating freedom of belief and thought, and their ideas laid the foundation for modern liberal perspectives on human rights, emphasizing the importance of a secular state and religious freedom.

John Locke’s A Letter Concerning Toleration, published in 1689, is one of the defining texts of this shift. The essay greatly influenced the development of the modern concept of the separation of church and state, which is entrenched in a number of modern constitutions. Locke’s argument was both philosophical and practical: he had come to the conclusion that persecution and punishment would never secure consent to the state religion, and so it was in the best interest of the state to let people worship as they pleased.

For Locke, the state existed to protect civil interests – life, liberty, and property – and had no legitimate authority over matters of the soul. Churches were voluntary associations, and no government had the right to compel a citizen’s conscience. It would be irrational to consent to a government that claimed a right to enforce a particular path to heaven, since that path might prove abhorrent to one’s own conscience.

Voltaire and the case against fanaticism 🔗

In France, Voltaire took a more combative approach. Voltaire savagely critiqued religious intolerance and clerical power, and his rallying cry against religious fanaticism became a watchword for those who saw institutional religion as an enemy of human progress. His Treatise on Tolerance (1763), written in response to the judicial murder of Protestant merchant Jean Calas, made a direct case that religious persecution was both irrational and inhumane. Where Locke had argued from political philosophy, Voltaire argued from outrage – and reached a wider public.

Legal milestones: from toleration to freedom 🔗

The Enlightenment did not just produce philosophy – it produced legislation. In England, the Toleration Act of 1689 gave freedom of worship to Protestant non-conformists who dissented from the Church of England yet pledged allegiance to Britain. It was a limited measure – Catholics and atheists were excluded – but it was the first time England legally acknowledged that religious diversity among Protestants was a permanent, acceptable feature of civil life. Locke’s Letter had helped frame the intellectual climate in which this became possible.

Across the English Channel, freedom to worship and civil rights for non-Catholics in France were not restored until the signing of the Edict of Versailles by Louis XVI on 7 November 1787. Two years later, the Declaration of the Rights of Man and Citizen (1789) went further, eliminating religious discrimination as a matter of constitutional principle.

The most sweeping legal achievement of the Enlightenment era came in the United States. The First Amendment of the American Constitution (1789) imposes the separation of church and state through its Establishment Clause, while the Free Exercise Clause prevents the state from restricting religious practices. This was no longer mere toleration – the grudging permission to let dissenting minorities exist – but a structural commitment to religious liberty as a right, not a concession.

From toleration to rights: a conceptual transformation 🔗

It is worth pausing on a subtle but important distinction. For most of the history traced here, “toleration” meant something quite specific: a dominant group permitting a minority to exist, without necessarily accepting or respecting them. In the Age of Enlightenment, to tolerate still meant to forbear something without liking it. Locke tolerated Protestant dissenters; he did not extend the same to Catholics or atheists. The Edict of Nantes tolerated the Huguenots; it did not treat them as equals.

The transformation from toleration to rights – from permission granted by the powerful to entitlements held by all – was gradual, and it was the Enlightenment that made it philosophically conceivable. By the end of the eighteenth century, figures such as Kant and Paine started to argue that toleration was opposed to true freedom, and that no authority had the right to declare an official religion and decide which religions should simply be tolerated. On this view, mere toleration was itself a form of condescension – it still presupposed that the state had the power to grant or withhold religious freedom, when in fact that freedom belonged to individuals by right.

This conceptual shift had real consequences. It pushed Western legal systems, however haltingly, toward the idea that the state’s role was not to manage religion but to stay out of it entirely. The long road from Rome’s pragmatic pluralism, through medieval inquisitions, the Wars of Religion, the Edict of Nantes, the Act of Toleration, and finally to the constitutional guarantees of the 18th century represents one of the most consequential transformations in the history of Western political thought.

What do you think? The West’s journey toward religious tolerance was driven as much by the failures of intolerance – war, economic loss, social fragmentation – as by philosophical ideals. Does that make the eventual outcome less principled, or does it simply reflect how political change actually happens? And given that the shift from “toleration” to genuine “freedom” took centuries, how confident should we be that current legal protections for religious minorities reflect a stable consensus rather than another fragile settlement?

References

1. https://teachdemocracy.org/online-lesson/religious-tolerance-and-persecution-in-the-roman-empire/
2. https://en.wikipedia.org/wiki/Religion_in_ancient_Rome
3. https://bvthomas.com/church-history/timeline-christendom-roman-empire-democracy/
4. https://merchantsandmechanics.com/2018/01/24/a-history-of-religious-toleration/
5. https://wjarr.com/sites/default/files/WJARR-2024-2442.pdf
6. https://www.britannica.com/event/Edict-of-Nantes
7. https://www.ebsco.com/research-starters/history/edict-nantes
8. https://www.worldhistory.org/article/2031/henry-iv-of-france–the-edict-of-nantes/
9. https://en.wikipedia.org/wiki/Edict_of_Nantes
10. https://www.britannica.com/topic/A-Letter-Concerning-Toleration
11. https://www.britannica.com/video/look-John-Locke-A-Letter-Concerning-Toleration/-202456
12. https://oll.libertyfund.org/pages/locke-on-religious-toleration-by-mark-goldie
13. https://americanheritage.org/philosopher-john-locke-and-his-support-for-religious-tolerance/
14. https://www.tandfonline.com/doi/full/10.1080/01916599.2016.1203590