Francis Turretin’s Natural Theology: Natural Theology’s Definition | John Sweat

by | Dec 8, 2023 | Apologetics, Historical Theology, Systematic Theology

*Editor’s Note: This is the fourth installment in a six-part series called “Francis Turretin’s Natural Theology.” As more installments are released, each part of the series will be linked to each post.

To read part 1 of 6, click here:

To read part 2 of 6, click here:

To read part 3 of 6, click here:

To read part 4 of 6, click here:

To read part 5 of 6, click here:

To read part 6 of 6, click here:



Defined and Delineated

Turretin opens his Institutes of Elenctic Theology dealing with prolegomena and the nature of theology.[1] According to Turretin, theology is both a discourse from God (as to source) and a discourse about God (as to its object), embracing the “twofold principle of theology”[2] In other words, theology, properly speaking, is “a system or body of doctrine concerning God and divine things revealed by him for his own glory and the salvation of men.”[3] In addition, Turretin argues that God alone meets the necessary conditions to be the object of theology.[4] And yet, when God is studied as the object of theology, it is God as he has revealed himself ectypally through divine revelation, revealing through Jesus Christ that he is the church’s God. As the object of theology, God is neither considered in himself, archetypally, nor generically as deity. The former is incomprehensible for creatures and the latter knowledge is deficient and damning to sinners, for a generic knowledge of deity is not sufficient for salvation nor a true knowledge of God. .[5] Van Asselt notes how the archetypal/ectypal model shapes the way the Reformed orthodox considered God as the object of theology,

Moreover, the previous discussion on archetypal and ectypal theology as an overarching paradigm indicates that the Reformed orthodox never used the term “Deus” (as the principium essendi of theology) in a neutral or unqualified sense in order to construe a natural theology in a rationalistic way. What is more, from the very beginning the triune God or Deus foederatus in Christo was envisioned by the Reformed orthodox in their discourse about God as the object of theology.[6]

Turretin and the Reformed orthodox considered the triune God who has revealed himself both in nature, Scripture, and in Jesus Christ as both the object of knowledge and the object of worship in true theology. Embedded in Turretin’s conception of theology is the emphasis that true theology is derived from God and depends on God to reveal himself, as the triune God of his people. Whatever he says moving forward concerning natural theology must be conditioned by this foundational starting point.

As seen with Junius, Turretin distinguishes theology into false and true theology, and then further divides true theology into archetypal and ectypal.[7] There are three modes of communication in ectypal theology: “the theology of union,” concerning the incarnation, “the theology of vision,” concerning the beatific sight of angels and saints in heaven, and “the theology of revelation,” concerning the pilgrims on earth.[8] It is under the last category that natural theology falls.[9] Also, Turretin includes a unique division of ectypal theology, unlike Junius, by dividing the school of God into three subjects with an accompanying three books of study. The “threefold school of God” is nature, grace, and glory with their respective books being the light of nature, the light of faith, and the light of glory. The first school belongs to men in the world; the second belongs to the church in the world; the third belongs to the glorified saints in heaven.[10]

Turretin does not treat natural theology as a pre-dogmatic foundation upon which supernatural theology must be built nor as an exercise of pure reason divorced from revelation. Turretin appears to say something contradictory to this that will be addressed later. But Turretin situated both natural and supernatural theology underneath the communication of revelation in ectypal theology.[11] Natural and supernatural theology are dependent on revelation, the former resting on natural revelation and the latter upon special revelation.[12]


Natural Theology Defined

Turretin does not give a definition of natural theology other than describing what it consists of, “The natural, occupied with 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).”[13] His description includes the phrase, “that which may be known of God,” noting natural theology’s dependence on God’s revelation in nature. Both the unregenerate and regenerate have this revelation (implanted in them), but only the regenerate moves from this revelation to a true natural theology. It is interesting to note at this point that Turretin does not expand on the distinction between natural revelation and natural theology. This may be in part because he includes in natural theology an innate knowledge, which is the internal aspect of general revelation in man that Paul speaks of in Romans 1:19, and he also includes acquired knowledge, which man receives by observing natural revelation. Turretin may have considered it unnecessary to elaborate on the distinction.[14] Nonetheless, natural theology is from God and about God, making God both the source and object.[15]  Natural revelation is the subject of natural theology, and natural theology consists of a twofold knowledge, innate and acquired. [16]

But what does Turretin mean by an innate and acquired knowledge? Turretin elaborates further on this twofold knowledge in natural theology by describing innate (or implanted)[17] as “derived from the book of conscience by means of common notions” and acquired as “drawn from the book of creatures discursively.”[18] Biblically, Turretin sees Psalm 19:1, Acts 14:15-17, 17:23 and Romans 1:19-20 as teaching that God has given to man a natural knowledge of God that is partly innate and partly acquired.[19] But the term “innate knowledge” can be taken in various ways. According to Muller, innate knowledge can refer to the seed of the religion (semen religionis) or the sense of the divine (sensus divinitatis) as a concept found in the Reformers and made more explicit in the Reformed orthodox. Innate knowledge does not refer to the Platonic theory of innate knowledge, cognito innata, nor does it refer to the sense of an infused knowledge leaving man as a tabula rasa[20] without this knowledge.[21] Furthermore, it is distinct from acquired knowledge, cognitio acquisita, which is gained mediately through the use of reason. The concept of innate knowledge used by the Reformed scholastics is cognition insita, which is an intuitive and immediate knowledge that is basic to the creature.[22] Michael Sudduth describes this knowledge as, “knowledge of God [that] is immediate, not a product of inference or argument, it involves theistic beliefs that are… properly basic.”[23]


About the Author

John Sweat is a marine veteran who serves as one of the pastors at Covenant Community Church in Lake Butler, Florida. He is a husband to Heather and a father to four girls. John has received an MA in biblical studies and an MA in Christian Thought at Gordon Conwell Theological Seminary.



[1] Refuting those that oppose the word “theology” since it is not found explicitly in Scripture, Turretin argues that all doctrine must derive from Scripture (concretely), but sound doctrine does not have to be expressly formulated with only the words of Scripture (abstractly). Turretin, Institutes of Elenctic Theology, 1.1.2-3.

[2] Turretin, Institutes of Elenctic Theology, 1.1.7. This twofold principle of theology in Reformed scholasticism is called the principium essendi (foundation of being) which is God and the principium cognescendi (foundation of knowing), which is Scripture. Muller, Dictionary of Latin and Greek Theological Terms, 290. This twofold principia was the essence of Christian theology that flowed out of the archetypal/ectypal distinction. God alone, the archetype, is the essential foundation of Christian theology, and his Word alone is the “cognitive foundation” as opposed to reason.  Muller, Prolegomena to Theology, 1:432–433.

[3] Turretin, Institutes of Elenctic Theology, 1.1.8. Turretin, like Junius, agrees that the word “theology” attributed to the false theology of the heathen and heretics is abusively and equivocally used. Turretin, Institutes of Elenctic Theology, 1.1.9; 1.2.5.

[4] Turretin, Institutes of Elenctic Theology, 1.5.1-3.

[5] Turretin in this section names Aquinas and the medieval scholastics generally as examples of the those who make the object of theology as deity generically. Turretin, Institutes of Elenctic Theology, 1.5.4.

[6] Van Asselt, “The Fundamental Meaning of Theology,” 334. Deus foederatus in Christo refers to God covenanting in Christ with his people mirroring Turretin’s comments above. See also Muller, Dictionary of Latin and Greek theological terms, 126.

[7] Turretin, Institutes of Elenctic Theology, 1.2.5-9. These categories have been sufficiently explored above and Turretin is in large part with Junius’ structure other than what has been indicated already.

[8] Turretin, Institutes of Elenctic Theology, 1.2.6. This follows in step with Junius threefold division of ectypal theology in theses ten through thirteen. Junius, A Treatise on True Theology, 119–120. Van Asselt highlights the christocentric nature of Junius’s, and by extension Turretin’s, ectypal theology when he writes, “Whereas archetypal theology is the matrix of all forms of theology, the theology of union is the mother (mater) of the two other forms of ectypal theology…” Van Asselt, “The Fundamental Meaning of Theology,” 331. Junius, A Treatise on True Theology, 129.

[9] Turretin, Institutes of Elenctic Theology, 1.2.7.

[10]  Turretin, Institutes of Elenctic Theology, 1.2.9.

[11] Turretin, Institutes of Elenctic Theology, 1.2.7.

[12] Muller, Prolegomena to Theology, 1:282, 272.

[13] Turretin, Institutes of Elenctic Theology, 1.2.7.

[14] Even as Turretin argues for the existence of natural theology, the arguments and Scriptural texts he employs typically are used as proofs for natural revelation, but Turretin uses them as proofs for natural theology. Turretin, Institutes of Elenctic Theology, 1.3.5-8.

[15] Though Turretin does not define natural theology in this way, by extension of his original definition of true theology it is consistent with his prolegomena. David Haines in his recent introduction to natural theology defines natural theology as follows, “that part of philosophy which explores that which man can know about God (His existence, divine nature, etc.) from nature alone, via man’s divinely bestowed faculty of reason, unaided by special revelation from any religion, and without presupposing the truth of any religion.” David Haines, Natural Theology: A Biblical and Historical Introduction and Defense (The Davenant Press, n.d.), 12. The problem with Haines’ definition is that he isolates natural revelation from special by denying the aid of Scripture, thereby restricting natural theology to pure reason and natural revelation. Further, he treats natural theology as a pre-dogmatic conception wherein man must reason from nature apart from any dogmatic commitments. But as seen in Calvin, Junius, and Turretin, a true natural theology is dogmatically conceived underneath ectypal theology and aided by supernatural theology. Third, even if it is granted that Haines is defining natural theology generically in order to include the unregenerate and the regenerate, he nowhere in the book makes the distinction between true and false natural theology. Last, his definition narrowly focuses on acquired knowledge and does not include innate knowledge.

[16] Junius in thesis fifteen defines natural theology as, “Natural theology is that which proceeds from principles that are known in relation to itself by the natural light of understanding, in proportion to the method of human reason.” Junius, A Treatise on True Theology, 145.

[17] He uses both terms interchangeably.

[18] Turretin, Institutes of Elenctic Theology, 1.3.4.

[19] Turretin, Institutes of Elenctic Theology, 1.3.6. Turretin goes on to argue for natural theology’s existence from Romans 2:14 which shows that all men have the natural law written upon their hearts and their conscience bears witness against them, implying a knowledge of God. Also, like Calvin, he points to the universal religion and worship of men as a proof for natural theology. Turretin, Institutes of Elenctic Theology, 1.3.5-14.

[20] Turretin grants that man’s mind is a tabula rasa relatively regarding dianoetical knowledge but he rejects it absolutely in regards to man’s intuitive or implanted knowledge. Turretin, Institutes of Elenctic Theology, 1.3.11.

[21] Muller, Prolegomena to Theology, 1:284-285. For a fuller definition of cognito innata or rasa see Muller, Richard A., Dictionary of Latin and Greek Theological Terms, 66–67, 354.

[22] Muller, Prolegomena to Theology, 1:285.For a fuller discussion on a distinction between immediate and mediate knowledge see Muller, Dictionary of Latin and Greek Theological Terms, 67–68.

[23] Sudduth, “Revisiting the ‘Reformed Objection’ to Natural Theology,” 43.

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God is Wise, and Hidden, and Revealed | Tom J. Nettles

God is Wise, and Hidden, and Revealed | Tom J. Nettles

Job mocks the repetitive irrelevance of the presentations of his comforters. He particularly derides the speech of Bildad for his restatement of the obvious that God is more powerful than his creatures. With seething sarcasm, Job quips, “How you have helped him who has no power!” Just telling me that God is stronger than I is neither enlightening nor particularly insightful in expanding our understanding of the ways of God with his creatures.

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