Lesson 7: The Canonical Horizon
Don't Think This Way
If you hear the term “systematic theology” and it means nothing to you, then this lesson was written for you. And if the term “systematic theology” gives you the heebie-jeebies, this lesson was also written for you!
We aim to stir up your desire to use systematic theology and to teach you how to do so, with extrabiblical resources, when interpreting Scripture. But before we get there, I’m going to warn you against two wrong ways to think about systematic theology.
Don’t think that systematic theology is less important than biblical theology.
Do you remember what biblical theology is? It is the branch of theology that interprets each unit of Scripture as part of God’s unfolding plan of redemption in Christ. Biblical theology takes “a narrative approach” to the whole of Scripture.¹ Like biblical theology, systematic theology aims to look at the whole of Scripture when interpreting individual passages. But systematic theology takes a logical approach. This approach considers what the whole Bible cumulatively says about a topic.
And this is necessary! The nature of Scripture requires both biblical theology and systematic theology:
The Bible’s nature as a unified collection of books written throughout the various stages of redemptive history requires biblical theology.
The Bible’s nature as a perfect thematic unity ultimately authored by God himself, revealing his eternal nature, requires systematic theology.
And while I’m still wrestling with how biblical and systematic theology relate, I’m confident that systematic theology is not less important than biblical theology.² In other words, we need both disciplines equally to interpret Scripture rightly.
For example, if we want to answer the question, “Who is God?” we cannot look only to biblical theology. Biblical theology explains what God has done to redeem a people for himself by focusing on the flow of redemptive history. But the Bible is not only a story; it is also the revelation of the nature of God—the One who is before and outside the story and the One who wrote and is directing the story. So the Bible teaches us about God not only by telling us what God does (creating the world, choosing Abraham, redeeming Israel, ultimately revealing himself most clearly in the gospel of Jesus Christ) but also by telling us who God is (giving many statements of fact about his nature).
Hear, O Israel: The LORD our God, the LORD is one. —Deuteronomy 6:4
So biblical theology shows us who God is as he reveals himself progressively through the story of Scripture, and systematic theology shows us who God is as he reveals himself propositionally in the statements of Scripture. Therefore, if we want to know God, we must turn to the whole of God's perfect revelation of himself in the Bible, both in its story and in its statements.
This is hard, unavoidable work! Nonetheless, as R.C. Sproul put it in the title of his introduction to systematic theology, “Everyone’s a theologian.” The only question is whether your theology is right or wrong!
So systematic theology is necessary, just like biblical theology.
Don’t think that systematic theology is artificial.
Some people think that when a theologian “systematizes” biblical doctrine, he is imposing foreign categories onto Scripture rather than simply interpreting what is already there. The flower may be beautiful, but it is artificial.
Now, it is true that the Bible doesn’t present its truth in a topical way. There is no “book of Christology,” or “book of ecclesiology.”
But if the Bible is a unified book, written by one perfect Author, then it does not contain any contradictions. Every part harmonizes with every other part. Systematic theology shows how the whole Bible coheres in the truths it declares, and this is God-honoring work.
However, not everyone harmonizes the teachings of Scripture correctly. The apostle Peter condemned those who “twist [hard teachings] to their own destruction,” calling them “ignorant and unstable” (2 Pet 3:16). Some people who use the tool of systematic theology use it in this dangerous, sinful way.
Such people are like Procrustes, that bandit in ancient Greek legend who offered travelers an iron bed to sleep on—a bed which he promised fit each person perfectly. But if a traveler was too long for the bed, Procrustes would chop off his legs so that he was the right length. And if a traveler was too short for the bed, Procrustes would stretch his body with ropes to make him the right length.
Today, we use the term “Procrustean bed” to describe an inflexible system, one that twists and stretches the truth to fit it. Instead, we want the truth to constantly form and reform our systems.
So beware of those who say that they have a simple system of doctrine that fits every text perfectly! The bed they lay each text on may be a Procrustean bed: any truth that doesn’t fit they either lop off or stretch out. As pastor and author Doug Wilson put it, “Illegitimate [systematic theology] is done by the kind of people who put together jigsaw puzzles with a pair of scissors and mallet handy.”³
But that is not what systematic theology is; it is what systematic theology has illegitimately become for some people. There are legitimate and illegitimate ways to practice medicine, just like there are legitimate and illegitimate ways to practice systematic theology. There are both good systematicians and bad systematicians, just like there are skilled doctors and quacks.
Systematic theology, done well, is not artificial but a demonstration of the living unity of Scripture.
How can you guard yourself from placing a difficult text of Scripture you’re studying on a Procrustean bed?
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