Arm yourself with evident proofs that there is a God. —Henry Scudder, 1627
“Natural theology” is a broad term referring to all religious knowledge that is accessible through reason, independently of supernatural revelation. It is therefore not limited to what can be known about God from contemplating the natural world, and it may also include other religious topics such as the existence of the soul, whether it is reasonable to expect an afterlife and Day of Judgment, and what some of our basic duties to God and one another might be. In the history of the Anglo-American Reformed
tradition, natural theology has often been presented jointly with arguments for the truth of the Christian religion specifically; for example, whether there are good reasons for believing that Jesus rose from the dead, that the Bible is a divine revelation, or that—given monotheism—a Trinitarian conception of God is more viable than a Unitarian one.
Advocates of natural theology believe that at least some of these arguments are good. In the case of deductive arguments, this would mean that they are sound; that is, that the premises are more reasonable to accept than to reject, and that the conclusions follow logically from the premises. In the case of inductive arguments, this would mean that theism (or some other truth about religion) is the best explanation of certain facts that are accessible to both believers and unbelievers.
Among both secular and Christian historians, the prevailing view about the history of natural theology within Protestantism has been what I have called the “assimilation narrative,” namely that both natural theology and the use of Christian evidences arose primarily in the eighteenth century as a response to the Enlightenment’s exaltation of reason and rejection of supernatural revelation. Faced with this development (it is thought), many Christian theologians, including those in the Reformed tradition, decided they also needed to find a way to ground their beliefs in reason. The “second chapter” to this story usually goes something along the lines that subsequent developments in philosophy and science showed these arguments to be untenable, forcing apologists to rethink their foundational premises. The secular historian will sometimes triumphantly cast this as a retreat from reason back into the realm of faith, where he thinks religion properly belongs. For the Christian historian, the story concludes with repentance: apologists realize that they (or their forbears) mistakenly left their true epistemological foundation of supernatural revelation. What both the secular and religious historian (of the assimilation-narrative persuasion) usually agree on is that the arguments of natural theology (as defined above) are not logically sound.
Post-Enlightenment Reformed Theology
So the question of who can more legitimately claim continuity with the Reformed tradition will turn on what thinkers in that tradition thought about natural theology prior to the Enlightenment. Click To Tweet With those introductory remarks, let me now turn to the history of natural theology in the Reformed tradition. I will begin with what is more recent, and non-controversial, and then work backwards in time to the Protestant Reformation. It is well known that near the end of the nineteenth and into the twentieth century, a number of Reformed theologians (and perhaps a majority of Reformed pastors) either rejected natural theology outright, or redefined it in such a way—namely as being dependent upon Christian presuppositions—that was tantamount to a rejection. One thinks of Karl Barth (1886-1968) in the “neo-orthodox” tradition (with which this article is not much concerned), Herman Bavinck (1854-1921), Cornelius Van Til (1895-1987) and Gordon Clark (1902-1985) most prominently among the orthodox Reformed (though there were some sharp differences between Van Til and Clark); and two of Van Til’s disciples whose works were widely read, Greg Bahnsen (1948-1995) and R.J. Rushdoony (1916-2001). John Gerstner (1914-1996) and his student, R.C. Sproul (1939-2017), were among the most well known modern Reformed advocates of natural theology.
It is also uncontroversial that most eighteenth- and nineteenth-century Reformed theologians warmly embraced natural theology. “Nothing is more certain,” wrote Jonathan Edwards (1703-1758), “than that there must be an unmade and unlimited being.” Natural theology infused the writings of the Old Princeton men. In his classic three-volume Systematic Theology, Charles Hodge (1797-1878) answered the question, “Can the Existence of God be proved?” in the affirmative, writing:
[T]he existence of God is an objective fact. It may be shown that it is a fact which cannot be rationally denied…. Most of the objections to the conclusiveness of the arguments in question arises from a misapprehension of what they are intended to prove. It is often assumed that each argument must prove the whole doctrine of Theism; whereas one argument may prove one element of that doctrine; and other arguments different elements. The cosmological argument may prove the existence of a necessary and eternal Being; the teleological argument, that that Being is intelligent; the moral argument that He is a person possessing moral attributes.
The works of William Shedd (1820-1894) and John Dick (1764-1833) also prominently feature the arguments of natural theology. “There are many books,” writes Dick, “in which [the existence of God] is evinced by arguments so strong and conclusive, that it is not easy to conceive how any man who has attended to them can continue an atheist.”
Natural Theology in the Puritans
The overwhelming majority of Puritans not only embraced natural theology on a theoretical level but put it to use in a surprising variety of pastoral, polemical, and missionary contexts. Click To Tweet So the question of who can more legitimately claim continuity with the Reformed tradition will turn on what thinkers in that tradition thought about natural theology prior to the Enlightenment. The assimilation narrative will not help us here because it is invalidated by what one of the most prominent, influential, and numerous group of pre-Enlightenment Reformed thinkers believed about natural theology. I am speaking of the Puritans, who pastored and wrote on both sides of the Atlantic from roughly the late 1500’s to the early 1700’s. Until recently, it was generally held that Puritans rejected natural theology. But as I showed in Puritanism and Natural Theology (2016), this turns out to be entirely mistaken. The overwhelming majority of Puritans not only embraced natural theology on a theoretical level but put it to use—along with evidentiary arguments for Christianity—in a surprising variety of pastoral, polemical, and missionary contexts. Even the small minority of dissenters did not categorically reject natural theology but merely expressed reservations about its usefulness. Arguments for the existence of God and the inspiration of Scripture were staple features of Puritan catechisms as early as the late sixteenth century and continuing to the early eighteenth. Thomas Vincent’s (1634-1678) didactic commentary on the Westminster Assembly’s 1647 Shorter Catechism, whose commendatory epistle was signed by 40 Puritans, is an example:
How doth it appear that God is true, that he hath a true being, or that there is a God indeed?
By several arguments, sufficient to convince all the Atheists in the world, if they would hearken to their own reason.
The epigraph taken from Henry Scudder’s The Christian’s Daily Walk (1627), one of the most popular devotional handbooks of the early seventeenth century, furnishes another example. This catechetical instruction had the two-fold purpose of establishing a foundation for Christian belief apart from the authority of the Roman Catholic church, and of helping parishioners who were struggling with doubt. As John Preston put it in the 1620’s while preaching on the existence of God:
And although it may be thought that there are none that doubt of this [the existence of God], yet these proofs are useful, partly because they serve to answer those secret objections of Atheism, which we are all subject to; and partly because they strengthen that Principle in us, that God is: which is very necessary to be confirmed, seeing it is the main and principal foundation of all Christian religion, and can never sufficiently enough be rammed down, as being that that must bear all the weight of the building. Therefore let no man think, that those proofs that we shall use for the manifestation of this truth, are a thing altogether needless.
As atheism and deism became more common after the middle of the seventeenth century, Puritans produced numerous apologetic treatises replete with arguments for the existence of God and the truth of Christianity: Richard Baxter’s Unreasonableness of Infidelity (1655), Reasons of the Christian Religion (1667), and More Reasons for the Christian Religion (1672); Matthew Poole’s Seasonable Apology for Religion (1673), Matthew Barker’s Natural Theology (1674), John Howe’s Living Temple (1675), William Bates’s Considerations of the Existence of God and Divinity of the Christian Religion Proved(1676 and 1677), Stephen Charnock’s Discourses Upon the Existence and Attributes of God (1682), John Ray’s influential Wisdom of God Manifested in the Works of the Creation (1691), John Flavel’s Reasonableness of Personal Reformation (1691), Cotton Mather’s, Truth of the Christian Religion Demonstrated, (1700), and his father Increase Mather’s Discourse Proving the Christian Religion (1702) and Discourse Concerning the Existence and Omniscience of God (1716).
Abraham Pierson (1608-1678) and John Eliot (1604-1690) made great use of natural theology and Christian evidences in their efforts to convert the Indians of New England. When Pierson undertook his mission to Quinnipiac natives on the north shore of Long Island in 1654, he prepared a treatise entitled, Some Helps for the Indians; Shewing them how to Improve their Natural Reason, to know the true God, and the Christian Religion, the first thirty pages of which were an elementary primer in natural theology and Christian evidences. This work was quickly translated into the Algonquian dialect for the use of Massachusetts Bay missionaries. It was also included in John Eliot’s A further accompt [account] of the progresse of the Gospel amongst the Indians in New-England (1659), for which the Puritan bishop Edward Reynolds wrote a preface, commending Pierson’s method as “a very proper and necessary course for those to take who would convert and persuade Pagans to believe the Truth.”
Puritans were especially confident in their arguments for the existence of God. One of their most prolific writers, John Owen (1616-1683), described these evidences as “infallible,” so that “whoever knoweth how to use and exercise his reasonable faculty in the consideration of them, their original, order, nature, and use, must necessarily conclude that so it is.” If anyone denied these arguments, he added, “it is a sufficient reply, in case he be so indeed, to say he is phrenetic, and hath not the use of his reason; and if he be not so [phrenetic], that he argues in express contradiction unto his own reason, as may be demonstrated.”
Puritans were especially confident in their arguments for the existence of God. Click To Tweet Even this small sampling of the evidence is sufficient to overturn the idea that what we now call a “classical” approach to natural theology and Christian evidences originated in the eighteenth century as a response to the Enlightenment. If we turn to the Continent during this period, one can add the great Francis Turretin (1623-1687), who strenuously defended natural theology against the objections of the Socinians: “The Orthodox, on the contrary, uniformly teach that there is a natural theology, partly innate (derived from the book of conscience by means of common notions) and partly acquired (drawn from the book of creatures discursively).” Nor does Turretin stop with natural theology, but he goes further to claim that arguments for the divine origin of the Bible, “though not sufficient for a full demonstration of the thing, are of great importance in its confirmation and in the conviction of unbelievers.” Peter Von Mastricht (1630-1706) outlines a “fourfold use” of natural theology, the second of which “has to do with pagans and atheists, who are most powerfully refuted by it.” Natural theology, he maintains, not only demonstrates the existence of God but also refutes polytheism and establishes our duty of worship.Already then, we have within the Reformed tradition a strong if not uniform affirmation of both natural theology and Christian evidences that stretches over a 300-year period from roughly 1600 to 1900.
Natural Theology in the Reformers
What about the earliest Reformers such as John Calvin (1509-1564), Ulrich Zwingli (1484-1531), Heinrich Bullinger (1504-1575), and Peter Vermigli (1499-1562)? Natural theology does not feature as prominently in their writings, but this is because responding to atheism was hardly at the forefront of their concerns. Indeed, it is questionable whether there were any genuine atheists in Europe prior to the seventeenth century. Nor was deism a considerable movement during this period. The polemical battle was against Roman Catholicism, and here their vital concern was establishing that the authority of the Scripture did not depend upon the authority of the church. Their answer—briefly—was that while there were good arguments for the inspiration of the Bible, and while the testimony of the church through history carried significant weight, yet Scripture carried its own immediate witness, through the voice of God speaking in it, and the operation of the Holy Spirit giving the regenerate full assurance of its truth. Turretin distinguished these as the “external” and “internal” arguments. The external arguments, said Calvin, were “neither few nor weak,” but he insisted that “of themselves these are not strong enough to provide a firm faith, until our Heavenly Father, revealing his majesty there, lifts reverence for Scripture beyond the realm of controversy,” and he added that “those who wish to prove to unbelievers that Scripture is the Word of God are acting foolishly, for only by faith can this be known.”
we have within the Reformed tradition a strong if not uniform affirmation of both natural theology and Christian evidences that stretches over a 300-year period from roughly 1600 to 1900. Click To Tweet Nevertheless, the earliest Reformers did routinely address the topic of natural theology, and when one reads these passages, it is hard to see any substantive difference from the views of their descendants over the following three centuries. Calvin is rapturous in his discussion of how the works of creation, and mankind in particular, are brimming with “innumerable evidences” of God’s being, wisdom, and power. Vermigli expresses himself similarly in his 1558 Commentary on Romans. Zwingli believed natural theology could even—through the grace of God—be sufficient to save pagans who had never heard the gospel, a view that drew the ire of Luther but received the tacit approbation of Bullinger.
There were, to be sure, some different shades of emphasis as the Reformed tradition developed. Among the Puritans, for example, one is more likely to find what I have called “rhetorical” condemnations of “reason” in the early period (pre-1640) than in the middle and later periods. Some were more comfortable than others in speaking of natural theology as a “foundation” for supernatural revelation. The arguments were expanded and refined in response to rising atheism and deism. But there is nevertheless a strongly unified tradition that exists until the emergence of the modern Dutch Reformed apologetic approach in the late 1800’s. The story of that development, and how it eventually captured much of American Reformed theology in the twentieth century, is a topic for another study. There is a strongly unified tradition that exists until the emergence of the modern Dutch Reformed apologetic approach in the late 1800’s. Click To Tweet
The Limits of Natural Theology
It should be emphasized that the classical Reformed approach to natural theology has always included an articulation of its proper limits. The logical strength of the arguments was one thing, their practical success in the history of ancient philosophy—absent supernatural revelation—another. Even at their full logical strength, they did not teach us the Trinity (though they might provide some hints and confirmation), show the way of salvation through Christ, or establish all of our Christian moral duties. Proving the existence of God did not imply comprehending him. There was a vital difference between things “contrary to reason” and “above reason.” The arguments for the inspiration of Scripture were secondary, and only preparatory to the full assurance afforded by work of the Holy Spirit. Most Reformed theologians held that no one could be saved without the knowledge of Christ, either because the Bible declares this to be impossible, or (Calvin is an example here) because natural theology reveals the justice of God but not his mercy and willingness to forgive. Some Reformed theologians thought God’s mercy was taught by natural theology, even if to a vastly lesser degree than in the Gospel, and a minority of them believed that there was nothing to prevent divine grace from occasionally bringing pagans to true repentance based on the knowledge afforded them by natural theology. These qualifications, it seems to me, address at least some of the common criticisms contemporary Reformed Christians have made against natural theology. There was a vital difference between things “contrary to reason” and “above reason.” Click To Tweet
There are two central Reformed doctrines, sola scriptura and total depravity, which some have suggested are inconsistent with natural theology. Sola scriptura is the doctrine that the Bible is the only absolute and binding source of authority for Christian belief. But this does not entail that it is the only source of belief and authority. Indeed, that quintessential Reformed document, the 1646 Westminster Confession of Faith, which opens with the doctrine of Scripture, begins that section by affirming that “the light of nature, and the works of creation and providence, do so far manifest the goodness, wisdom, and power of God, as to leave men inexcusable.” The Bible itself teaches the validity of natural theology. To the clause just quoted, the Westminster divines footnote two loci classici, Romans 1:19-20 and Psalm 19:1-4, as proof texts. Paul reproves the Corinthians for needing apostolic instruction for what they should have learned from nature: “Does not even nature itself teach you…?” (I Cor. 11:14).
As for “total depravity,” when modern people hear this term, it is natural for them to think it is synonymous with the common phrase “totally depraved.” However, in its theological meaning, “total” refers to the extent, not the degree, of depravity, and it means that the effects of original sin extend to all the faculties of the human person. This would include human reason, which Reformed theologians have maintained was injured in two ways by the fall. The first was a diminishment of our ability to think logically, so that even with a renewed heart and will, we may be prone to logical errors in our reasoning. This disability could be partly remedied in this life, said the early English Puritan Thomas Spencer (fl. 1628-1629), by studying logic—which natural theology is of course an exercise in. The second injury, remaining in the regenerate but dominating in the unregenerate, is moral, where our reasoning is distorted when a train of solid argumentation points to truths we do not wish to accept. As another Puritan, William Bates, described it, “the corrupt Will bribes the Mind to argue for what it desires.”
But neither of these defects undermine the enterprise of natural theology. The intellectual defect, as just mentioned, is helped by natural theology. The moral defect, to be sure, needs the fundamental healing of conversion, which according to Reformed theology requires a supernatural operation of God’s grace. But this by no means invalidates the various means and preparations God may use to bring a person to that point, whether it is natural theology, the attractiveness of a group of Christian people, experiences of art, love, and so forth. Nor should the benefits of natural theology be measured only by whether it leads to Christian conversion. Even if it did no more than keep atheism at bay and maintain a general fear of God in the population, it would be an entirely worthwhile enterprise, parallel to the “second use of the law,” which the Reformed have always maintained. Moreover, there is another space, beyond conversion and restraint of civil evil, where natural theology and Christian evidences have been eminently useful, and that is in strengthening the faith of believers and helping to support it in times of doubt. The strength of the testimony of the Spirit varies widely among Christians, and as we know from both the Bible and church history, even those who enjoy it in the highest degree have sometimes been subjected to a “dark night of the soul” where it seems to disappear. As Richard Baxter put it:
I perceive, that because it is taken for a shame, to doubt of our Christianity and the Life to come, this hindereth many from uttering their doubts, who never get them well resolved, but remain half Infidels within, whilst the Ensigns of Christ are hanged without [i.e., on the outside]; and need much help, though they are ashamed to tell their needs….
The best complain of the imperfection of their Faith: And too many good Christians, especially if Melancholy surprise them, are haunted with such temptations, to Atheism, blasphemy and unbelief, as make their lives a burden to them! And one that hath heard so many of their complaints as I have done, is excusable for desiring to relieve them.
These brief remarks are not an exhaustive treatment of theological concerns that might be raised about the enterprise of natural theology, to say nothing of epistemological objections, which again would be a topic for another article. But I hope it is enough to show that in adopting natural theology, Reformed theologians have not been unmindful of their other theological commitments. In conclusion, I think it is fair to say that while there is a significant vein of Reformed thinking, now more than a century old and with many contemporary adherents, that is opposed to natural theology, the mainstream of the Reformed tradition, viewed across its 500 years of history, is predominantly in favor of both natural theology and Christian evidences. We can further affirm that this orientation was not born of an impulse to accommodate Enlightenment concerns, but was rather an integral component that was present from its origin and consistent with its central theological doctrines.
 For examples of the assimilation narrative, see my Puritanism and Natural Theology (Eugene, Ore.: Wipf and Stock, 2016), 4-6, 135-136.
 Jonathan Edwards, “Miscellanies,” # 1340.
 Charles Hodge, Systematic Theology, 3 vols. (Grand Rapids, Mich.: Eerdmans, 1986 [orig. pub. 1872-73]), 1:202-203.
 John Dick, Lectures on Theology, 4 vols. (Edinburgh: William Oliphant & Son, 1834), 1:18. For Shedd, see his Dogmatic Theology, ed. Alan W. Gomes (Phillipsburg, N.J.: Presbyterian and Reformed, 2006), 127-150, 169-171, 201-218.
 Thomas Vincent, The Shorter Catechism of the Westminster Assembly Explained and Proved from Scripture (Carlisle, Pa.: Banner of Truth, 1998 [orig. pub. 1673]), 35. Among the signatories were John Owen, Joseph Caryl, Matthew Barker, and the three Thomas’s—Manton, Watson, and Brooks.
 John Preston, Sermons Preached Before his Majestie; and upon other speciall occasions (London: Printed for Leonard Greene, 1630), 66.
 The Eliot Tracts: With Letters from John Eliot to Thomas Thorowgood and Richard Baxter, ed. Michael P. Clark (Westport, Conn.: Praeger, 2003), 325.
 John Owen, The Reason of Faith, in The Works of John Owen, ed. William H. Goold, 24 vols. (London and Edinburgh: Johnstone and Hunter, 1850-55), 4:87, 89.
 Francis Turretin, Institutes of Elenctic Theology, ed. James T. Dennison, Jr., 3 vols. (Phillipsburg, N.J.: Presbyterian and Reformed, 1992), First Topic, Q. 3, IV (p. 6); Second Topic, Q. 4, VII (p. 63).
 Peter Von Mastricht, Theoretical-Practical Theology, 3 vols. (Grand Rapids, Mich.: Reformation Heritage Books, 2018-2023), 1:179 (quotation), 183.
 Calvin, Institutes, 1.9.13.
 See my “Salvation for the Unevangelized in the Reformed Tradition” (forthcoming).
 See my discussion of this topic in Puritanism and Natural Theology, 11, 59-68.
 Westminster Confession of Faith, I.1.
 Thomas Spencer, The Art of Logick, Delivered in the Precepts of Aristotle and Ramus (London: Printed by John Dawson, 1628), “To the Reader,” iii; William Bates, Considerations of the Existence of God, and of the Immortality of the Soul (London: Printed by J. D. for Brabazon Aylmer, 1676), vi.
 The first use of the law is for conviction of sin, the second is to restrain evil, and the third is to aid our sanctification.
 Richard Baxter, Reasons of the Christian Religion (London: Printed by R. White for Fran. Titon, 1667), “To the Reader,” ii–iii.