Deism: The Religion of Nature and Reason in the Enlightenment

In the spring of 1696, a twenty-five-year-old Irishman named John Toland published a book with the deliberately provocative title Christianity Not Mysterious. The book argued, with the brisk confidence of the young, that the whole edifice of Christian supernaturalism was a late accretion; that the original gospel had been a perfectly rational religion, and that whatever could not be understood by ordinary human reason ought to be discarded. The book was ordered burned by the Irish Parliament. The author was, as he cheerfully noted in later prefaces, “well pleased” — persecution was, by this point, practically a credential.

Toland was a deist. He belonged to a loose coalition of writers, mostly British and French, who shared a few core commitments: there is a God, God created the universe, God set its laws in motion, and God then — to put it bluntly — left it alone. From this followed the rejection of special revelation, the rejection of miracle, and a deep suspicion of any church that claimed to mediate between the worshipper and the divine. The deist was, in a slogan that became famous in the eighteenth century, a “believer in God” who was not a Christian, not a Jew, not a Muslim, and not an atheist — a position that pleased almost no one and that has, perhaps for that reason, been quietly influential ever since.

What deism actually was

The conventional summary — God as cosmic watchmaker, then stepping back — is not wrong, but it is a little too tidy. The deists were not unanimous. Some, like Matthew Tindal in his 1730 Christianity as Old as the Creation, argued that the religion of nature was the original religion, and that Christianity, stripped of its later corruptions, was simply a republication of natural religion in a particular time and place. Others, like Voltaire, treated deism more as a usable position than a worked-out theology: he was happy to affirm a Creator God and a moral order, but he made fun of metaphysics in general, and his personal religion probably came down to a few sturdy moral principles and a polite incomprehension of the Trinity. Jefferson, late in life, took a pair of scissors to the four Gospels and pasted the moral teachings of Jesus into a small red notebook — keeping the ethics, deleting the miracles. This is what deism looked like in practice: not a system but a stance.

A useful way into the substance is the argument from design. In its mature eighteenth-century form, especially in William Paley’s 1802 Natural Theology, the argument ran: the complexity of biological organisms (the eye, the heart, the watch on the heath) is so striking that it must be the product of intelligent design rather than chance. The argument was not new — Cicero had used a version of it, so had the medieval theologians — but the deists made it the load-bearing premise of their rejection of miracle. If the universe is governed by stable laws, then a God who constantly intervened to suspend those laws would be either an indifferent mechanic or a celestial busybody. The deist preferred a God who had got the design right the first time and was now letting it run.

The other deist weapon: the critical Bible

The second deist innovation was historical. Spinoza’s Tractatus Theologico-Politicus of 1670 was the founding text. It applied to the Bible the same kind of textual-historical scrutiny that was being applied to classical manuscripts, and it concluded that Moses almost certainly did not write the Pentateuch, that the prophetic books are composite, and that Scripture everywhere reflects the historical conditions of its composition. Richard Simon, a French Oratorian, developed a parallel line of argument in the 1680s. The English deists — Toland, Tindal, Thomas Woolston, Matthew Tindal again, Anthony Collins — pushed further. Voltaire, in his Dictionnaire philosophique (1764), reduced much of the Old Testament to a record of “barbarism and absurdity,” and the book sold enormously.

The result was a Bible that, for the deists, was a human document containing a mixture of truth and error, with the moral teachings worth preserving and the supernatural claims fit for the dustbin. The argument was intellectually serious. It was also politically dangerous. The deist critique of miracle is, in substance, the position of David Hume in Section X of the Enquiry Concerning Human Understanding (1748), and Hume’s argument was written in part because he thought the existing deist case had not been pushed hard enough.

Edward Herbert and the natural-religion minimum

It is conventional to date the deist movement to Edward Herbert, Lord Herbert of Cherbury (1583–1648), whose De Veritate of 1624 set out what he claimed were five common articles of natural religion: the existence of God, the obligation to worship God, the importance of virtue, the duty to repent of sin, and the existence of future rewards and punishments. These were, he said, common to all religions and discoverable by reason alone.

Herbert is the kind of figure that historians either treat as the founder of a tradition or as a polite footnote, depending on their temperament. The case for treating him as a founder is weak: he wrote in a philosophical vocabulary that was not widely available, and his English successors — Toland, Tindal, Collins, Woolston — claimed him as a forerunner rather than as a direct influence. The case for treating him as a footnote is also weak: his De Veritate was widely read across Europe, translated into French and other languages, and cited by virtually every eighteenth-century deist. The honest judgment is that Herbert mattered more as a brand than as a thinker. He gave the deists a respectable ancestor and a five-point manifesto, which is roughly what a movement needs.

The major figures, in their actual temperaments

Voltaire (Voltaire) is the only deist most readers will have heard of, and the reason is that he was a much better polemicist than a theologian. His actual philosophical position was thin. He believed in a God who had designed the universe and who rewarded the virtuous in some vague afterlife, and he had nothing much to say about it. What he was brilliant at was the ridicule of organized religion — the infamies, the miracles, the absurdities — and at turning the case for toleration into a sustained moral campaign. The Calas affair, in which a Protestant merchant was tortured to death in Toulouse in 1762 on the absurd charge of having murdered his son to prevent his conversion to Catholicism, made Voltaire into a European figure and made religious toleration into a cause with a body count.

Thomas Jefferson was a more systematic deist than Voltaire, and a much colder one. The Notes on the State of Virginia (1785), the Jefferson Bible (compiled in 1820 from the moral teachings of Jesus), and the correspondence with John Adams show a mind that had stripped Christianity down to a deist skeleton: a benevolent Creator, a moral code, a reward for virtue, and nothing miraculous. Adams was a Unitarian who sometimes pushed back; Jefferson held his ground. The two old men, both retired from public life, used the late-eighteenth-century postal service to conduct a long-running seminar on the existence of God and the meaning of Jesus.

Benjamin Franklin was the most pragmatic of the lot. His Autobiography records his gradual movement from his mother’s strict Calvinism to a working deism, with the emphasis on working: he read the Sermon on the Mount and kept it; he rejected predestination and original sin because they struck him as useless for the conduct of life; he was, in his own phrase, “a thorough deist” by the time he was fifteen and never saw reason to change. Franklin’s deism was the kind a busy, practical man might hold — a moral framework and a habit of skepticism, with no particular interest in what exactly God was doing with His creation.

What the deists actually believed

Despite the diversity, a few common articles can be extracted. (1) There is a God, and the natural world is the product of intelligent design. (2) No particular religion has privileged access to divine truth. The Bible, the Koran, and the Vedas are all human documents, with a mixture of truth and error. (3) Miracles do not happen. Hume’s argument is the strongest version of this position, but it was already implicit in the deist picture of a God whose design works through unbroken natural law. (4) Organized religion, as a political force, is dangerous. The churches have accumulated wealth, power, and a vested interest in keeping the laity ignorant. (5) The religion of nature is, at its core, a religion of morality. The proper way to serve God is to be decent to other people.

The deist position on the political power of the church was, in the eighteenth century, the radical edge of the doctrine. The Americans — Jefferson, Franklin, John Adams, James Madison — put it into the Constitution. The First Amendment’s prohibition of religious tests for public office and its bar on the establishment of religion are direct descendants of the deist campaign. The French, more violently, attempted to dismantle the Catholic Church and replace it with a Cult of the Supreme Being, which Robespierre installed in 1794. The Cult was deism with a civic calendar and a state festival; it did not survive the fall of Robespierre.

The four great critiques

Deism was attacked from four directions, and the attacks are still instructive.

The orthodox critique came from Christian, Jewish, and Islamic apologists, and it had a simple structure: you cannot dismiss the historical evidence for revelation on the basis of philosophical arguments about the regularity of nature. The miracle at the Red Sea and the resurrection of Jesus are historical claims, and a philosophical argument about what sorts of events are likely does not refute a witness who claims to have seen one. The deists knew this. Their answer was that the regularity of nature is itself a defeater of miracle claims, since the prior probability against any specific miracle is so high that no amount of testimony can overcome it. The argument is still going on.

The philosophical critique came from inside the deist camp. Hume’s Dialogues Concerning Natural Religion (1779, published posthumously) subjected the design argument to a withering examination: even if we grant that the universe has the marks of design, the best we can conclude is that it has a designer, not that the designer is omnipotent, omniscient, or even one. The watch on the heath was a bad analogy: the watch has a designer we know; we have no such knowledge of the universe. Kant’s Critique of Pure Reason (1781) reached a parallel conclusion by a different route: the traditional proofs of God’s existence are rationally inconclusive.

The Romantic critique came from Herder, the Schlegel brothers, Schleiermacher, and the broader German Romantic reaction against the Enlightenment. The complaint was that deism reduced religion to a set of propositions about the natural world, and that the actual religious life of human beings — ritual, community, the sense of the infinite in the finite, the dependence on what Schleiermacher called “the feeling of the universe” — was missing entirely. The complaint was unfair, but it was not empty. The deists did have a thin account of religious experience, and they had no good answer to the question of why, if natural religion was sufficient, human beings had spent several thousand years producing something so much more elaborate.

The historical critique came from nineteenth- and twentieth-century scholarship. The deist account of “the religion of nature” as the original and universal religion has not survived the discovery that the actual history of religion looks nothing like that. There is no pristine natural religion underneath the historical religions; there is a tangle of practices, myths, rituals, and social institutions that resist exactly the kind of rational extraction the deists attempted.

Was the deist project worth it?

Pocock has argued, in the spirit of his larger work on the Enlightenment, that the deist campaign was the founding act of modern secularism — that the separation of the moral and natural orders from the supernatural was the move that made modern liberalism possible. Jonathan Israel’s more recent scholarship pushes the credit in a different direction: he assigns the priority to Spinoza and the radical tradition, with the deists as the popularizers rather than the originators. Skinner, in his later work, has come closer to Pocock. The debate is not closed.

What can be said is that the deists got two things substantially right: organized religion, when fused with political power, is a serious threat to civil peace; and the appeal to revelation, as a way of settling contested questions, is a much weaker form of argument than the appeal to reason and experience. The deists got two things substantially wrong: they underestimated the depth of the religious impulse in human life, and they overestimated how far reason alone could carry a moral and political order. The modern secular state is, in part, a deist invention. It is also a deist problem.