In light of a recent work on natural theology, especially since it seeks to represent the Reformed tradition as rejecting natural theology, we will take some time doing expositional reading of some from the Reformed tradition on the topic of natural theology. As we begin, it is important to recognize several things. First, the Reformed tradition does not equate to Calvin’s Institutes. This is an important misconception in many sectors of both proponents and opponents of Reformed theology. Just as neither William Perkins nor John Own equate to Puritanism—they are important representatives—nor does Calvin equate to Reformed theology or the Reformed tradition. Thus, when we seek to represent the Reformed tradition, we should not feel compelled to rely exclusively on Calvin. This is not to say either that Calvin should not be read, nor that Calvin’s thought is not of particular importance, nor that Calvin disagreed with those who succeeded him. It is simply to say that efforts that seem to rely solely on Calvin should be received with a dose of skepticism.
The second important thing to recognize is that natural theology has breadth, and that its use, abuse, and rejection by various thinkers are often contextualized. Thus, when natural theology is on the ascendency, sometimes going so far as to basically result in Deism or Theosophy or something along those lines, we should expect to find harsher statements about its usefulness, while we should expect devolutions into fideism, or “communal knowledge,” to result in stronger statements about its reality. Thus, some today are speaking quite strongly for natural theology specifically because we live in an age of Postmodernism, both in its various non-Christian cultural expressions and in expressions within the church. Thus, when we read the men of the past, we see them expressing different emphases, as expected, based on whether they’re confronting something like Socinianism on the one hand or Enlightenment philosophy on the other. (Those are broad terms, of course, that have their own emphases also).
Third, it is important to recognize in the earlier Reformed that they do not speak of a “failure” of natural theology, but of a “weakness” of natural theology. Natural theology only goes so far. In the end, it demonstrates the reasonableness of belief in the existence of God, and therefore the folly of unbelief, but it does not teach the essentials of the faith such as the Trinity or how man is saved. A great example of this is seen in Amandus Polanus, Syntagma Theologiae Christianae, I.X, in which he differentiate between supernatural theology and natural theology. Unfortunately, it’s only available in Latin at this time. (It may be worth noting that he does favorably cite Thomas Aquinas’s Summa, 1.1.1). Paired with the previous important note, we should expect then that the weakness may be variously emphasized by different authors based in part on who they’re engaging.
These caveats, or prolegomenal points, in place, here we offer a summary of Turretin’s explanation of natural theology.
After describing the fact the most important distinction in theology, namely “archetypal” and “ectypal,” or God’s knowledge of himself, he then argues that the second applies to three different forms (theology of union, theology of vision, and theology of revelation [Institutes of Elenctic Theology, 1.2.6]). For the last of these, he says, “the theology of revelation is again divided into natural and supernatural” (IET, 1.2.7). He then says there are two aspects are included in discussion of natural theology, namely, “that which may be known of God (to gnōston tou Theou), is both innate (from the common notions implanted in each one) and acquired (which creatures gain discursively).” He summarizes this introduction to what theology is with this very helpful statement:
As there is a threefold school of God (that of nature, grace and glory), and a threefold book (of the creature, of Scripture and of life), so theology has usually been divided into three parts: the first of which is natural, the second supernatural and the third beatific; the first from the light of reason, the second from the light of faith, the third from the light of glory. The first belongs to men in the world, the second to believers in the church and the last to the saints in heaven. IET, 1.2.9.
In developing the idea of natural theology, after admitting that man has the faculty of discursively knowing God though growing in that knowledge, Turretin then contrasts the Reformed (whom he calls “the orthodox”) with Socinians. Socinians (according to Turretin) taught that all acquired knowledge of God was actually partially from tradition (from Adam on) and partially from various special revelations. Turretin then asserts: "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 [koinas ennoias]) and partly acquired (drawn from the book of creatures discursively). And they prove it by the following arguments” (IET, 1.3.4). Quite honestly, it is difficult to see how his statement in that section doesn’t introduce a dividing line between two parties debating today, one of which would seem to align more closely with Socinians’ view than (using Turretin’s term) “the orthodox.”
Turretin follows these statements with some arguments that point to both the innate and discursive aspects of the knowledge of God and his law, including the conscience and existence of religions. The next question (IET, 1.4) tackles the serious issue of whether anyone can be saved by means of natural theology, to which Turretin obviously answers “No” in contrast to Socinians, Arminians, and even some “Papists.” Since that’s not the question we’re dealing with here—we’re concerned to show that he affirms natural theology itself, not the abuses—we close with Turretin’s summary affirmation of natural theology’s usefulness:
[W]e acknowledge [natural theology’s] various ends and uses: (1) as a witness of the goodness of God towards sinners unworthy even of these remains of light (Acts 14:16, 17; Jn. 1:5); (2) as a bond of external discipline among men to prevent the world from becoming utterly corrupt (Rom. 2:14, 15); (3) as a subjective condition in man for the admission of the light of grace because God does not appeal to brutes and stocks, but to rational creatures; (4) as an incitement to the search for this more illustrious revelation (Acts 14:27); (5) to render men inexcusable (Rom. 1:20) both in this life, in the judgment of an accusing conscience (Rom. 2:15) and, in the future life, in the judgment which God shall judge concerning the secrets of men (Rom. 2:16). IET, 1.4.4.