We need to recognize other foundations that compete with Scripture. Here are several common foundations for theology: human reason, human emotions, (i.e. man’s likes and dislikes, loves and aversions, hopes and fears), dreams, visions, or a so-called “Inner Light”, church history and/or tradition, superstition, oral tradition, and legends, Roman Catholic Magisterium, and personal experience. 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.  These are not the God-ordained means of his special revelation to us. Sources of knowledge derived from man’s experience will often be misguided and can even be malevolent. 

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.

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]

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]

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:

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).

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