How Firm a Foundation: Building Theology on the Solid Ground of God and His Word


What do the following phrases all have in common?

“I know exactly what heaven is like, because I read a book about a kid who died and went there and came back to life.”

“God paying for our sins by sacrificing his son doesn’t make logical sense.”

“I just can’t believe in a God who would send people to suffer in hell forever.”

“The Holy Spirit told me to divorce my spouse and marry my co-worker.”

“The Pope now allows priests to bless same-sex unions, so they must be OK in God’s eyes.”

They all represent a statement that arises from a way of doing theology that lacks strong foundations. Consider our Lord’s declaration in his Sermon on the Mount:

Why do you call me ‘Lord, Lord,’ and not do what I tell you? Everyone who comes to me and hears my words and does them, I will show you what he is like: he is like a man building a house, who dug deep and laid the foundation on the rock. And when a flood arose, the stream broke against that house and could not shake it, because it had been well built (Luke 6:47–48, emphasis added).

Only a faith-filled response to Jesus’s words and an eagerness to obey them builds a flood-resistant foundation for the Christian life. And this applies to Christian theology too.

In order to do theology rightly, we have to get our fundamental principles right—what has traditionally been called the theological principia.[1] To do this, we have to undertake an excavation of sorts. We need to dig deep and investigate the foundation of our theology. What will we find? Where does theology itself come from and how can we come to know it? Let’s get started.

1. I contrast “foundation” and “principle” conceptually, but the Greek/Latin words are not exactly synonymous. See Herman Bavinck’s brief but concise summary of the development of this term. Bavinck, Reformed Dogmatics, 1:210­–12.

The Two Theological Principia

The two principles (principia) of theology are God and his revelation. These two, in different ways, comprise the proper foundation, source, or beginning of all theology, albeit in different ways.

  • God is the “essential foundation” of theology—theology’s ultimate Source, or principle of being (i.e. principium essendi).
  • God’s Written Revelation (Scripture) is the “cognitive foundation” of theology—theology’s principle of knowing (i.e. principium cognoscendi).

Theology, therefore, necessitates the unflinching assumption that God has made himself known in a way accessible to his creatures.[2] Theology is, as the medieval adage declares: “taught by God, teaches God, and leads to him.”[3]

2. These principles are ontological and epistemological, respectively.

3. The quote is often attributed to Thomas Aquinas. See it used by Geerhardus Vos, Biblical Theology: Old and New Testaments, 18 and Francis Turretin, Institutes of Elenctic Theology, I. Q.1, VII.

Now, there is a bit more say. Who is this God that is theology’s principium essendi? And in what sense do we humans need to utilize the proper principium cognoscendi? With some simple definitions now in hand, let’s brush off any dust and debris from these principia and lift our magnifying glass to them.

The Principium Essendi: The Essential Foundation of Theology

First, there is a classic distinction in the history of theology between archetypal and ectypal theology. Archetypal theology is “God’s own knowledge concerning himself,” while ectypal theology is “a sort of copy of the former.”[4] The kind of theology we seek to know and teach—in our books, articles, and sermons—is an ectypal theology from God that “belongs to pilgrims, who are on earth.”[5]

4. Van Mastricht, Theological-Practical Theology, 1:76.

5. Van Mastricht, Theological-Practical Theology, 1:76. Van Mastricht goes on to offer the traditional distinction within an ectypal, or “pilgrim” theology, between “natural” and “revealed.” Christian theology he calls “revealed theology.” Van Mastricht, Theological-Practical Theology, 1:77. It should also be noted that Van Mastricht, following the traditional Reformed scholastic position, understands “pilgrim theology” to be only one species of ectypal theology. For the various and sometimes complex distinctions made regarding ectypal theology, see Richard Muller, Post-Reformation Reformed Dogmatics, Volume 1: Prolegomena to Theology, 225-237.

This distinction is critical to properly understand because it leads us to consider the difference between God’s knowledge and our own. According to Scripture, there is an unfathomable, awe-inspiring difference between our knowledge and God’s—so much so that we ought to be led like Paul to declare: “Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways” (Rom. 11:33)!

Indeed, God’s knowledge is something only he can plumb the depths of, as Paul would go on to ponder through Isaiah: “For who has known the mind of the Lord” (Rom. 11:34)? While no man can know it, this infinite, comprehensive, and utterly true and right knowledge that God has of himself is shared perichoretically (amongst the three persons of the Trinity),[6] demonstrating it to be an eminently personal and thus able-to-be-shared knowledge:

6. On the doctrine of perichoresis, see Kevin DeYoung’s “Theological Primer: Perichoresis,” The Gospel Coalition.

But, as it is written, “What no eye has seen, nor ear heard, nor the heart of man imagined, what God has prepared for those who love him”—these things God has revealed to us through the Spirit. For the Spirit searches everything, even the depths of God. For who knows a person’s thoughts except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God (1 Cor. 2:9–11).

The Spirit himself “searches” the depths of God and so shares in his infinite knowledge with perfect comprehension, as does the eternal Son (Matt. 11:27). This incomprehensible, personal, rational, coherent, and divine self-knowledge is the source of all God’s revelation to his creatures. Cornelius Van Til therefore rightly taught that there are “two levels of knowledge.”[7] There is “the level of God’s knowledge, which is absolutely comprehensive and self-contained, and the level of man’s knowledge, which is not comprehensive but is derivative and reinterpretive.”[8]

7. One grasps the seriousness with which Van Til took this issue in his debate with Gordon Clark. For reference, check out the podcast “The Clark/Van Til Controversy,” Reformed Forum.

8. Van Til, An Introduction to Systematic Theology, 33. This distinction arises in Van Til’s treatment on human knowledge as analogical (by way of analogy). In so doing, he makes the compelling case that “in all non-Christian theories men reason univocally [assuming that human concepts can map onto God without any difference in meaning], while in Christianity men reason analogically.” Van Til, An Introduction to Systematic Theology, 31–36. In my judgment, Van Til’s utter rejection of correlativism, (i.e. any position that posits change in God as a result his relation to creation), places him deeply within the stream of classical Reformed thought.

In sum, “[n]o knowledge of God is possible except that which proceeds from and by God (Matt. 11:24; 1 Cor. 2:10ff) . . . The fact that the creature knows anything of God at all is solely due to God.”[9] It is only from the infinite well-spring of this “other level” of God’s own knowledge—his archetypal theology, our principium essendi—that pilgrim theology springs. We must, therefore, in our theology, strive to think God’s thoughts after him.[10]

The Cognitive Foundation of Theology

Recognizing then that the depth of God’s knowledge is infinitely vast, it is nevertheless true that the Spirit of God searches these depths and freely reveals true knowledge accommodated to man’s finite and sinful frame (Deut. 29:29). This revelation is our principium cognoscendi, our source of theological knowledge. But what, we might ask, is the nature of this revelation?

Before we survey the integrity of our cognitive foundation for theology, we must clear off some dirt and grime. In order to get to the one true foundation, God’s Revelation in Scripture, we need to recognize other foundations that compete with Scripture. Here are several common foundations for theology.[11]

9. Bavinck, Reformed Dogmatics, I:212.

10. Bavinck said eloquently that “a theologian’s sole responsibility is to think God’s thoughts after him and to reproduce the unity that is objectively present in the thoughts of God and has been recorded for the eye of faith in Scripture.” Bavinck, Reformed Dogmatics, I:44 (emphasis mine). One can also find this phrase throughout the corpus of Cornelius Van Til, who was greatly indebted to Bavinck.
  1. Human Reason
  2. Human Emotions, (i.e. man’s likes and dislikes, loves and aversions, hopes and fears)[12]
  3. Dreams, Visions, or a so-called “Inner Light”
  4. Church History and/or Tradition
  5. Superstition, Oral Tradition, and Legends
  6. Roman Catholic Magisterium
  7. Personal Experience
11. Points one through six of this list draw from one of W. H. T. Dau’s three lectures delivered at Concordia Seminary in 1942. See W. H. T. Dau, “False Principia Cognoscendi in Theology,” Concordia Theological Monthly 13, no. 9 (September 1942): 654–61. Space limits a further elaboration on these seven faulty foundations. But it suffices to observe that when they are utilized as foundations for knowing, they are destructive to right theology.

12. I especially liked Dau’s comment regarding this false principia: “A theologian who is swayed by his natural emotions is inclined to offer to his clients the delightful aspects of Christianity and soft-pedal its sterner demands. That will put them on a spiritual sugar diet and raise a type of namby-pamby, good weather Christians that wilt in the heat of trials and perish in the cold blasts of popular disfavor.” Dau, “False Principia Cognoscendi in Theology,” 657.

While each of these sources of knowledge may reveal some truth or truths about God, none of them can bear the weight of being the ultimate source of knowledge. Without the clear and present testimony of God’s inspired Word, all of them will result in error—great and small. Consider a few examples:

  • Some may craft their theology of heaven based upon children who died, went to heaven, and then came back to life to report what they saw. This theology would be grounded in the fraudulent foundation of either #2 or #7.
  • Others may allow their doctrine of salvation, hell, or election to be informed more by how revolting it seems to them or whether or not it is “logically” consistent. If these concerns are fundamentally driving their theological convictions, then their theology is grounded in the false foundation #1 or #2 above.
  • Still others may make decisions about who Jesus is, what he is doing, or when he will return based upon some dream (#3), superstition (#5), or teaching from church history (#4). In such cases, the sincerity of the belief does not eliminate the error. It only restricts the adherent’s ability to reject the false foundation.

Ultimately, all of these are false principia, and here is why. First, these are not the God-ordained means of his special revelation to us. And, second, man is sinful and corrupt, which means that sources of knowledge derived from man’s experience—his or those who have gone before him—will often be misguided and can even be malevolent. Therefore, we need to embrace God’s special revelation in his Word (an external reality) and be spiritually enlightened to receive truths we are naturally resistant toward or unable to grasp (an internal reality). Let’s consider both.

Two Realities for Knowing God

First, the Word of God in Scripture is the external principle of knowing (i.e. principium cognoscendi externum). This is God’s appointed means of communicating himself to his people. All of the data for our theology, so to speak, is contained with the pages of Scripture. Yet it isn’t merely data to comb through like a detached statistician. Through God’s verbal inspiration, Scripture reveals his own voice (2 Tim. 3:16), richly textured through many authors, genres, covenants, and typological structures, through a God-glorifying redemptive story from beginning to end. God’s Word is a refuge for the weary soul (Ps. 119:28), but also the foundation and source for our knowledge of him, for our theology and doctrine (1 Tim. 6:3).

Second, the Holy Spirit’s work to enlighten our eyes (Eph. 1:18) to the truths of Scripture is the internal principle of knowing (i.e. principium cognoscendi internum). Our sin and finitude prohibit us from joyfully receiving by faith what God has revealed to us, and thus the Holy Spirit is sent to apply this revelation, as well as bring about a systematic coherence and harmony of these divine truths to the human understanding. Certainly, this second principle of knowledge requires the first, but the first, left to itself, is unable to properly ascertain true encounter with the Living God.

Thus, while some popular, yet fraudulent, principia urge themselves upon us to build our theological house upon them, we must be warned that they are not flood-resistant foundations. Instead, a biblically formed, and therefore strong, cognitive foundation depends upon the external principle of God’s Word and the internal principle of illumination.


In summary, we have surveyed the foundations, or principia, of faithful Christian theology. Simply, there are two principia, God and his revelation in Scripture. Yet as we dig in deeper and sweep away the debris, we find that a proper cognitive foundation has two aspects to it—the Word and the Spirit. Thus, along with Bavinck, we can declare:

We have discovered three foundations (principia): First, God as the essential foundation (principium essendi), the source, of theology; next, the external cognitive foundation (principium cognoscendi externum), viz., the self-revelation of God, which, insofar as it is recorded in Holy Scripture, bears an instrumental and temporary character; and finally, the internal principle of knowing (principium cognoscendi internum), the illumination of human beings by God’s Spirit.[13]

This concluding observation leads to one final, marvelous insight from Bavinck, namely, that these three principia “are rooted in the trinitarian being of God.”[14] While “distinct yet essentially one,” these principia reflect what we might call the triune God’s theological mission toward his Church: “It is the Father who, through the Son as Logos, imparts himself to his creatures in the Spirit.”[15] Theology is a divine gift, and one that leads us to the God who gives himself to us!

13. Bavinck, Reformed Dogmatics, 1:213.

14. Bavinck, Reformed Dogmatics, 1:214.

15. Bavinck, Reformed Dogmatics, 1:214.

From beginning to end, true theology is of our triune God—from him, to him, and through him. To him be the glory forever and ever. (Rom. 11:36). Let us, therefore, lay a strong foundation in our labors of knowing God and doing theology.



  • Robert Lyon

    Robert Lyon is a PhD student in Systematic Theology at the Southern Baptist Theological Seminary (SBTS) in Louisville, Kentucky. For the past decade he has worked as an engineer in the manufacturing industry. He holds a Master of Divinity from SBTS, as well as undergraduate degrees in Computer Science and Mathematics from Indiana University. Robert is married with three children and a member of Hunsinger Lane Baptist Church.

Robert Lyon

Robert Lyon

Robert Lyon is a PhD student in Systematic Theology at the Southern Baptist Theological Seminary (SBTS) in Louisville, Kentucky. For the past decade he has worked as an engineer in the manufacturing industry. He holds a Master of Divinity from SBTS, as well as undergraduate degrees in Computer Science and Mathematics from Indiana University. Robert is married with three children and a member of Hunsinger Lane Baptist Church.