Smith explains the origins of deism and its basic ideas.

George H. Smith was formerly Senior Research Fellow for the Institute for Humane Studies, a lecturer on American History for Cato Summer Seminars, and Executive Editor of Knowledge Products. Smith’s fourth and most recent book, The System of Liberty, was published by Cambridge University Press in 2013.

In some previous essays in this series I had occasion to mention deism and some particular deists, such as Shaftesbury, Anthony Collins, and Charles Blount. It is now time that I explain this movement—and it is, I think, proper to call deism a “movement”—and its doctrines.

During its heyday in the eighteenth century, deism was closely affiliated with classical liberalism; and more than a few deists, such as John Toland, were active in the radical wing of liberalism, sometimes called radical (or real) whiggism, or (in the case of those liberals who rejected monarchy altogether) radical republicanism. For example, two writers familiar to many libertarians—John Trenchard and Thomas Gordon, authors of the libertarian classic Cato’s Letters—wrote many anticlerical tracts, most of which appeared in their journal The Independent Whig. And though, like most deists of their time, Trenchard and Gordon never expressly repudiated Christianity, they called for a return to “primitive Christianity,” that is, a return to the moral teachings of Jesus, which every deist praised. (Paul was the favorite New Testament target of deists, primarily because he developed the doctrine of original sin.) According to this typical deistic agenda, we should reject the irrational doctrines and practices that had been added to primitive Christianity by self‐​serving priests and theologians; instead we should embrace the pure, undefiled moral teachings of Jesus. According to the deists, the essence of Christianity is moral behavior, not belief in dogmas about “mysteries,” such as the Trinity, that no one can understand or rationally justify.

In 1754 the English Presbyterian minister John Leland published A View of the Principal Deistical Writers, a book that he later expanded into two volumes. In this work, which became the standard secondary source on deism for many years, Leland traced the label “deist” to 1563, when it was used in a book by the Swiss Calvinist Peter Viret. Leland got his information from the massive and highly influential Historical and Critical Dictionary, by the infamous skeptic Pierre Bayle (1647–1706). Bayle’s Dictionary (which today would be called an encyclopedia) provided a goldmine of information for Enlightenment freethinkers, including information about some very obscure figures. In the article on “Viret” Bayle quoted a lengthy passage written by Viret in which he lamented the rise of a new species of unbelievers in France who called themselves “deists.” This passage reads, in part:

I hear that some of this band call themselves Deists, a new word in opposition to that of Atheists. For the word Atheist signifies one that is without God, so they would hereby signify, that they are not without God, because they believe that there is one, whom they even acknowledge for creator of Heaven and Earth, as well as the Turks: but as for Jesus Christ, they do not know who he is, nor do they believe in him or his doctrine. These Deists of whom we speak ridicule all religion, though they accommodate themselves to the religion with whom they are obliged to live, out of complaisance or fear: some among them have a kind of notion of the immortality of the soul; others agree with the Epicureans on that as well as on the Divine providence with regard to mankind: they think he doth not intermeddle with human affairs, and that they are governed by fortune, or by the prudence and folly of men, according as things happen.

Viret was distressed because some of the self‐​styled “deists” also called themselves “Christians,” despite their total rejection of supernatural revelation. (This practice would persist throughout the history of deism, thereby generating the problem of who was really a Christian and who was not.) Viret was also puzzled because many of the deists were highly educated.

I am struck with horror, when I think that there are such monsters among those who bear the name of Christians. But my horror is redoubled, when I consider that several of those who make profession of learning and human Philosophy, and even are frequently esteemed the most learned, most acute and most subtle genius’s, are not only infected with this execrable Atheism, but also profess to teach it, and poison several persons with this venom.

Viret had ridiculed the beliefs of Catholics and Muslims, but he sensed that the deists would not be so easy to dispose of, especially since they explicitly repudiated atheism—a position that virtually no one in the sixteenth century would embrace. The ongoing conflict between Protestants and Catholics gave Europeans two religions from which to choose, and Viret had no doubt that Protestantism had the upper hand from a biblical perspective. (Islam, which Viret condemned as a type of idolatry, was not a realistic candidate.) But the deists had muddied the waters by offering the third option of no religion at all, in effect, despite their belief in a God of nature.

Wherefore we live in a time when we are in danger of having more difficulty in contending with these monsters, than with the superstitious and idolators, if God doth not, which I hope he will, prevent it. For amongst the present difference in religion, several very much abuse the liberty given them of choosing which of the two contending religions they will adhere to. For several are of neither, and indeed live without any religion. And if those who have no good opinion of any religion, would content themselves to perish alone in their error and Atheism, without infecting or corrupting others by their wicked discourses and example, and leading them into the same perdition with themselves, this evil would not be so deplorable as it is.

Deism became popular in England around the same time as in France and Holland. In one of the best histories of deism ever written, The Dynamics of Religion (2nd ed., 1926), the freethought historian J.M. Robertson attributed the rise of deism to a widespread disillusionment with the practical effects of Christianity. Many people had become sick of the incessant internecine conflicts among Christians themselves—the intolerance, cruel persecutions of heretics, witch‐​hunts, and bloody wars that had plagued Europe since the Reformation. Robertson (pp. 65–66) wrote:

Of such general distaste for Christian dogma in the France of 1650, and in the England of 1660–1730, there seems to be only one explanation—namely, that the very extremity of religious feeling, the long frenzy of mutual malevolence, the stupendous failure of a professedly love‐​inculcating religion to make men so much as consent to let each other alone, much less to love one another, had sent many men on questioning whether the game was worth the candle; whether this creed, which caused blood to flow like water was any more divine in its special dogmas than that of Mohamet, or those of pagan antiquity. Educated men simply grew sick of the religious temper, of religious phraseology, of religious books, of religious principles; and even those who remained orthodox tended to take on a new tone of secular ratiocination….

Although deism emerged simultaneously in several countries, it was English deism that was destined to exert the most influence. Whereas many French freethinkers veered in the direction of outright atheism, especially during the eighteenth‐​century Enlightenment, the majority of eighteenth‐​century English freethinkers took the less disturbing route of defending the existence of a benevolent God who created the universe but who thereafter adopted a laissez‐​faire policy, leaving the universe alone to operate according to natural laws. It was this English tradition that influenced leading American deists, such as Thomas Jefferson, James Madison, and Benjamin Franklin; and when Thomas Paine published his notorious defense of deism, The Age of Reason (published in two parts, 1794, 1795; with a third part—a criticism of biblical prophecies—added in 1807), he drew heavily from his English predecessors, such as Anthony Collins.

Edward Herbert (Lord Cherbury) has traditionally been called the “father” of English deism. In 1624, while serving as England’s ambassador to France, Herbert published De Veritate (On Truth). This book lamented the disunion and disarray of Christianity, which had splintered into a “multitude of sects, divisions, sub‐​divisions, and cross‐​divisions.” Herbert proposed a solution: five “common notions” which, he argued, are found in all great religions and which would therefore unite them in a common cause. Without these common notions, “it is impossible to establish any standard in revelation or even in religion.” These common notions enable us to pare down all religions to their essentials and thereby eliminate many needless and divisive dogmas: “Some doctrines due to revelation may be, some of them ought to be, abandoned.” Herbert’s attempt to isolate the core precepts of a true religion, and his disdain for superfluous doctrines supposedly based on divine revelation, became recurring themes in later deistic writings.

Herbert spurned some common claims about religion—for example, that reason must be abandoned to make room for faith, that the church is infallible, that one should not trust one’s own judgment in religious matters, that to doubt religious claims is sinful, and so forth. Such precepts, Herbert pointed out, will support false doctrines as readily as they support true doctrines.

Now these arguments and many similar ones…may be equally useful to establish a false religion as to support a true one. Anything that springs from the productive, not to say seductive seed of Faith will yield a plentiful crop. What pompous charlatan can fail to impress his ragged flock with such ideas? Is there any fantastic cult which may not be proclaimed under such auspices?

According to Herbert, clergymen who “base their beliefs upon the disordered and licentious codes of superstition” are like “people who with the purpose of blinding the eyes of the wayfarer with least trouble to themselves offer with singular courtesy to act as guides on the journey.” In religion as elsewhere we should follow our own reason, not the judgments or commands of others. Indeed, God “requires every individual to render an account of his actions in the light, not of another’s belief, but of his own.” This call for independent judgment would become the hallmark of deism and of freethought generally.

Herbert’s five common notions functioned as standards to judge alleged revelations as true or spurious, so that “the genuine dictates of Faith may rest on that foundation as a roof supported by a house.” His five notions were as follows:

(1) “There is a Supreme God.” Even in polytheism, Herbert contended, a supreme god is recognized. This supreme god is blessed, the cause of all things, good, just, and wise. (2) “This Sovereign Deity ought to be Worshipped.” (3) The only indispensable features of religion are virtue and piety. (4) Sins must be expiated by repentance (and, by implication, predestination is incompatible with the justice of God—a slap at Calvinism.). (5) “There is Reward or Punishment after this life.”

According to Herbert, if a religion does not conform to these five notions, then it is not good, nor does it provide a means to salvation. The key to salvation is moral conduct, not belief in sundry dogmas. “For how could anyone who believes more than is necessary, but who does less than he ought, be saved?”

Although some of Herbert’s five notions were embraced by later deists, some were not. (Some deists did not believe in an afterlife, for example.) Moreover, in some respects the later writings of John Locke, especially his empiricist theory of knowledge, exercised a far greater influence on deistic thought than Herbert ever did. Nevertheless, Herbert got the ball rolling, especially with his argument that the function of religion, first and foremost, is to serve as a guide for moral conduct. For the first several decades of the eighteenth century the debate between deists and Christians was the most contentious and most widely discussed issue in England. And that debate, as we shall see, was chock‐​full of political implications.