Natural theology has been understood primarily, if not exclusively, as arguments for the existence of God.

However, as the name suggests, natural theology is nothing other than the study of God “in the things that have been made” to use Paul’s exact words in Romans 1:20. If theology is the study of God and nature is the shorthand word we use for the creation, then this is a very reasonable definition of natural theology.

We could say that natural theology corresponds to general revelation in that general revelation is the objective speech of God in all creation. So general revelation is the divine action and natural theology is the human action. It is human rational reflection on divine information. Since we are finite and sinful, we are not surprised to find that there is true natural theology and false natural theology.

Ralph McInerny’s definition is among the most helpful:

“Natural theology … means the philosophical discipline which proves that God exists and that he has certain attributes. It is theology because it is concerned with God, and it is natural because it makes use of our natural powers unaided by any supernatural revelation.”1

What Natural Theology is Not

As David Haines has pointed out, natural theology is not logically coextensive with (1) natural revelation, (2) natural religion, or (3) apologetics as such.2 For that reason, we ought not confuse natural theology with these. This distinction between natural theology as such versus its apologetic use will be absolutely critical. What I am proposing is nothing less than the all-pervasive use of natural theology in the whole of theological encyclopedia. This is what it will mean to have reason and nature “at the foundation” of theology.

We must disentangle natural theology from modern caricatures.

Natural theology got a bad rap, so to speak, in two major philosophical waves. First, the triumph of Nominalism at the end of the Middle Ages; and second, the triumph of Kantian subjectivism in the modern era. The first of those reduced universals (e.g. “beauty,” “justice,” “goodness,” “oneness,” “truth,” etc.) to being merely names that we assign by abstract reasoning, rather than being essential metaphysical realities. Consequently, even philosophers began to do their reasoning from the particulars of this world alone.

The second of those historic waves restricted our access to any objective “way that things are,” independent of the mind. Kant’s Critique of Pure Reason (1781) severed the connection between reason and the essence of things. Consequently, theological content could no longer be about eternal realities that all minds could speak about and of which we could compare our notions. Metaphysical philosophy and theology were no longer viewed as tenable, and one was left to simply presuppose the things of God in a way that was sufficient for religion or ethics or science. For the irreligious man, even those “spiritual” things were no longer things, yet for the religionist, the basic subjective (or perspectival) method was the only option left.

By and large the church has followed the thinking of this Nominalist-then-Kantian shift. Hence natural theology also received a bad name within the church. It too was treated subjectively, as if “it” was “doing” some desperate climbing up to God from the perspectives of natural man.

By the turn of the twentieth century, it was common to associate natural theology with the “natural religion” of the Enlightenment. Karl Barth condemned it as vain speech of a natural deity, and a rejection of the transcendent. 

If we can summarize J. V. Fesko’s recent work on the subject, Cornelius Van Til lodged five main criticisms of Thomas Aquinas that really parallels almost all arguments against natural theology:

(1) Reliance on Aristotle’s philosophy in general; 

(2) Proofs of God’s existence according to logic, and thus Aristotle;

(3) Proofs from common ground conclude a God of natural reason; 

(4) No need of supernatural revelation to correct the natural man’s grasp of natural revelation; 

(5) Two Thomases, one of philosophy (thus autonomous reasoning) and one of theology: the latter unable to correct the former.3

We disagree and insist, in the first place, that natural theology is taught in Scripture: cf. Romans 1:19-20, 2:14-15, Psalm 19:1, Acts 14:15-17, 17:23. Whether natural theology may utilize the tools of the Philosopher, and in what ways, is a very important question. However, even if we severely restricted Aristotelian categories in the study of God in nature—indeed, even if we attempted to filter out all of the Philosopher’s language—we would still be stuck with the words of Scripture that tell of God making himself known in intelligible ways through the created order.

According to Van Til, all general revelation does is to make sinners inexcusable, but “how this natural knowledge functions to bring about their inexcusability”4 is a thorn to such a view. The suppression of this knowledge because of sin is more proof that the knowledge is obtained, in order that the will may be blameworthy in its suppression. This word κατεχόντων that Paul uses denotes an active and intentional suppression of knowledge. So we cannot say that these common notions about God are simply an inner “sense of the divine” that is not reasoned knowledge. There has to be a rational-intentional “Yes … but,” for the suppression to be real and blameworthy. 

The Principal Stumbling Block for the Post-Van Tillian Reformed

Inevitably when the subject of natural theology comes up in the Reformed camp of the past two or three generations, the concept is hopelessly conflated with soteriology. That theology is “natural” comes to mean that natural man is reasoning his way to God. This is not unique to the Van Tillians, as I indicated above. There have always been fideists in all Christian traditions, for whom faith must function as an alternative epistemological ground so as to make sure that no one else make reason function as a soteriological ground. Anyone who has been in such conversations begins to realize that it is a fear-driven category mistake that cannot be de-escalated.

But the wisdom of the historic Reformed tradition would teach the Van Tillians that the question is not soteriological. For instance, Francis Turretin wrote about natural theology that,

“The question is not whether this knowledge is perfect and saving … but only whether any knowledge of God remains in man sufficient to lead to believe that God exists and must be religiously worshipped.”5

Note Turretin’s exact words. Natural theology is simply a discipline with a particular subject matter. When you talk about it, you are doing it. When you argue for God, you are doing it. When you argue against God, still doing it. When you argue against doing it—yes, even here, you are still doing it. That is to say, you are 1. using extra-biblical language, 2. assuming extra-biblical data, 3. to ascribe all manner of predicates 4. to extra-biblical objects that 5. God says are about God (revisit Romans 1:20).

Likewise, Turretin argued, this knowledge of God is not only that he exists but that he ought to be worshiped. If you have ever heard that statement by C. S. Lewis, that we cannot call a line crooked without the idea of a straight line—so it is here, that the unbeliever cannot fashion reasons for God’s non-existence, nor suppose that he is a being unworthy of worship without a “straight line” to distort. Furthermore, Turretin argued for natural theology against the Socinians and maintained that “the orthodox” hold to natural theology. Now why those Socinians denied natural theology is subject for another day, but it certainly is interesting that the classical Reformed thinkers would make such a point. 

I would also add that the question is not revelation versus reason. Paul is clear in Romans 1:19 that what may be known about God is plain because God has made it so. In other words, all right reasoning is a function of revelation.

Making a Full Recovery of Natural Theology

Fesko argues against Van Til in a way that I personally find insufficient. Fesko follows the scholarship of Richard Muller in this, namely that the five ways of Aquinas “function only on the presupposition of faith and the authority of Scripture.”6 What does he mean by this?

Thomas’ first question, before the proofs, is on the nature of sacred doctrine, in which he insists upon the necessity of divine revelation to surpass that which reason cannot attain; “So then,” he argues, “sacred doctrine makes its case from faith, not reason.” The role of reason, he argues, is as a handmaid to faith.

Certainly we can agree to using such language in one sense. Reason plays a ministerial, rather than a magisterial, role in relation to faith. But how precisely is Fesko understanding this distinction? It seems to me that, even among many who are recovering classical theological categories, that there is a demonstrable “demonstrataphobia” going on. That is, there is a reluctance to have reasoning functioning at the foundations of either arguments for God’s existence or for one’s system of doctrine. But why is this?

According to this view, the role of reason does two things. It (1) answers objections and (2) clarifies revealed truths—as if rational demonstration is neither of those categories, or at least, as if rational demonstration cannot proceed from premises rooted in nature (outside of Scripture, or not already assented to “by faith”). However, we insist that positive demonstrations are within those categories. They both answer and clarify. They both refute skepticism and build belief. They certainly do not replace faith where the will must trust God, nor comprise an “autonomous reason” that is inventing one’s own truth. One may indeed be guilty of that, but it simply doesn’t follow by the nature of the case.

In other words one can demonstrate various things about the two main principia categories (God and Scripture) without ever departing from revelation. And one can do so precisely from extra-biblical grounds. One reason for that we have already seen—namely, that there is nothing in true logic or metaphysics that is not first revealed. Now one way to smooth all of this over is to maintain that God’s existence is a preamble to, and not an article of, faith. But the main point is summarized by Thomas,

It seems that a man cannot know any truth without grace … The natural light bestowed on the mind is God’s light, by which we are enlightened to know such things as belong to natural knowledge.7

Sproul, Gerstner, and Lindsley put Thomas’ validation of natural theology by Scripture in a more classical light. The classical approach is “not here basing the validity of natural theology upon the Bible. We have not yet demonstrated that the Bible is in fact special revelation or that the Bible teaches natural theology. What we are doing at the moment is pointing out that if the Bible is special revelation and if it teaches natural theology then, of course, by irresistible logic we must conclude that natural theology is valid.”8

No doubt the Van Tillian will object at this very point. They want to insist that such natural theology must subject the Bible’s authority to whatever comes before that first ‘if’” or else what we have is autonomous reasoning.

In addition to missing the classical apologist’s point, this reveals another odd category mistake in the presuppositionalist critique of natural theology. In simple terms, antecedents are confused with authorities, such that if A comes before B in any line of reasoning (particularly when A is outside of the Scriptures and B is a truth in the Scriptures), then A has functioned as an “authority over” B. So, to be clear, logical antecedents are conflated with moral authorities or even allegiances.

Having said that, the only point that the authors of Classical Apologetics were making about Thomas was that he could both 1. believe that natural theology was valid because the Bible taught him to expect it and 2. hold that arguments for either God’s existence or the divine inspiration of Scripture validly begin with all manner of extra-biblical antecedents.

What exactly are the objects of natural theology? Simply saying God does not quite help: first of all because Paul specifically mentions “eternal power and divine nature,” and furthermore, “in the things that have been made.” Fesko has written much in his recent book about what used to be called common notions. Simply stated, these are notions “ingrafted in all men’s hearts” including (1) the existence of God and (2) the difference between good and evil. I do not personally prefer language that suggests only a pre-packaged set of principles when talking about this, but that is a finer distinction for another day. Fesko’s strength is chronicling the overwhelming testimony of the Reformed tradition that is at one with the classical tradition.

But from a Reformed Classicalist perspective, there are questions that remain. There are at least three areas in which the present recovery (most notably represented by Fesko’s book) leaves us with an insufficient view:

(1) [Common] notions do not require proof because they are self-evident.”9

(2) A division of common notions between 1. principles and 2. conclusions, with no connection in objective natural theology.

(3) Natural theology, as preamble for faith, may or may not be prolegomena for dogmatics.

What exactly is the point of saying that common notions do not “require” proof? One may think that is itself self-evident! After all, if a truth is self-evident, then no self would ever need it proven. Case closed, right? But there are two immediate problems with leaving things at that. The first is that radical skepticism in every age has denied this. The second is this “requirement” is ambiguous and begs the question as to whether demonstration is not a wider category than this subjective “need” or “requirement.”

I will leave Fesko’s second and third points for the query of another day (i.e. my own upcoming doctoral dissertation). They are standard categories in Reformed prolegomena and require in-depth analysis to get at the right views. Let us end with application to classical apologetics as such. 

As long as there has been Christian theology there has been natural theology. Various arguments for God’s existence are already found in the works of Plato, Aristotle, and Plotinus. The earliest apologists, Anaxagoras, Tatian, and Justin Martyr made use of them. They were given more Christian structure in Augustine, Boethius, and Anselm, and then greatly elaborated upon among the Scholastics of the Middle Ages. For example, in the most widely studied text of late medieval theology, the Sentences of Peter Lombard, four ways to discern God’s existence are offered. Roughly speaking, these move (1) from design to a Designer, (2) from mutability to the Immutable, (3) from the supremacy of spirit over body to the Maker of both, and (4) from the supremacy of intelligence over mere perception to the all-seeing Mind. I say “roughly speaking” because Peter’s section here lacks the precision of standard treatments of natural theology. For instance, in his first way he does not specifically use the word “design,” nor the term “all-seeing Mind” in the fourth.

In all of these movements of reason, we are moving from sign to substance; or, from the created things analogous to God, to the divine things that are attributes of God. I mention these early examples partly because of the perennial myth that such rigorous attempts to use reason to demonstrate God’s existence did not begin with Thomas Aquinas. Nor does such a project end with Hume and Kant. 

The authors of Classical Apologetics issued a call for the “reconstruction of natural theology.”10 Reformed Classicalism is dedicated to this very thing. The purpose is twofold. If natural theology is what we suggest here, then both apologetics and our system of doctrine will proceed only from speech about God that is objective and necessarily the case. Having established the altogether non-negotiable God of the Bible, there is no wiggle room either for the skeptic peddling his endless alternative realities, or for the pseudo-theologian always in search of a more immanent deity. 

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1. Ralph McInerny, Characters in Search of Their Author: The Gifford Lectures, Glasgow 1999-2000 (Notre Dame, IN: University of Notre Dame Press, 2001), 5.

2. David Haines, Natural Theology (Landrum, SC: Davenant Press, 2021), 12-16.

3. J. V. Fesko, Reforming Apologetics (Grand Rapids: Baker Academic, 2019), 73.

4. Fesko, Reforming Apologetics, 52.

5. Turretin, Institutes, I.3.3

6. Fesko, Reforming Apologetics, 75.

7. Aquinas, quoted in Sproul, Gerstner, & Lindsley, Classical Apologetics (Grand Rapids: Zondervan, 1984), 25.

8. Sproul, Gerstner, & Lindsley, Classical Apologetics, 36.

9. Fesko, Reforming Apologetics, 30.

10. Sproul, Gerstner, & Lindsley, Classical Apologetics, 64-90.