Systematic theology is the discipline of looking to the entire Bible to determine what God says about a given topic. It answers the question “What does the whole Bible say about __________ [fill in the blank]?” It is a logical, systematic way of organizing truth. To be skillful, accurate theologians, we need systematic theology, but we must also be aware that its strengths are closely related to its weaknesses. Fire is valuable for producing heat and energy, yet fire’s heat and energy is exactly what makes it dangerous. The problem is not fire, but allowing fire to get out of control. This is also the case with systematic theology.
In his book How to Understand and Apply the New Testament: Twelve Steps from Exegesis to Theology, Andy Naselli explains 10 strengths (and 10 corresponding dangers) of systematic theology. I’ve condensed and at times quoted it with his permission. I’ve also included a list of our personal recommendations for the best systematic theology books.
1. It can enrich your understanding of a text (but also distort it).
Carefully reading a text to analyze what its author intended to communicate tends to focus on the details while systematic theology tends to focus on the big picture. The first sees the trees while the second sees the forest. You are never a neutral, objective investigator of a text because when you read, study, and interpret it you already have a systematic, theological grid through which you see it. A good reason to study systematic theology is to improve the theological grid through which you see the text. If your systematic theology is sound, then it can enrich how you interpret a particular text. But if your systematic theology is too weak, too simple, or too speculative it can actually distort how you interpret a particular text.
2. It can give you an accurate theological grid (or an inaccurate one).
Systematic theology can provide Bible interpreters with an accurate theological grid. This is a tremendous gift, but a gift that can be abused. Instead of treating systematic theology as a servant, you can allow it to become the master. You can become preoccupied with a system rather than the Bible, and that’s just a step away from giving more weight to the system and letting it substitute for the Bible.
3. It can precisely identify doctrinal tensions (or wrongly resolve them).
God is infinite and eternal while we are finite and fallen. God is so far beyond us that we should not expect our minds to be able to perfectly grasp his works and ways. A strength of systematic theology is that it helps you precisely identify doctrinal tensions, but a corresponding weakness is that these tensions can tempt people to wrongly or tritely resolve such tensions.
4. It can help you harmonize texts (but lead you to develop a “canon within the canon”).
Bringing harmony to various Bible passages is what systematic theology is all about. It can help you correlate how a particular text harmonizes with others, but a corresponding danger is that you can develop your own “canon within the canon”—your own list of favorite passages that you think are most important and that operate like a controlling interpretive grid. When this happens, your systematic theology controls your interpretation of the text. Instead of having a “canon within the canon” we are to let Scripture interpret Scripture. The Bible doesn’t contradict itself, so a sound principle is that we should interpret less clear passages in light of more clear passages. We shouldn’t zoom in on just one text and interpret it without reference to the rest of the Bible but interpret the unclear in light of what is more clear.
5. It can helpfully address contemporary issues (but overlook the text because it is further removed from it).
For systematic theology, the biblical text is important, but other factors often set the agenda. It asks such questions as these: What does the whole Bible say about creation and evolution? (Such a question often arises from a person’s cultural context in which naturalistic evolution is what the culture assumes to be true.) What does the whole Bible say about marriage and homosexuality? (Such a question often arises in light of a person’s personal journey or interactions with a friend or in light of current events.) What is the eternal destiny of people who die without ever hearing the gospel? (Such a question often arises from skeptics looking for reasons to discredit the Bible or from genuine Christians who are trying to make sense of what seems unjust.) Those are all questions that you need systematic theology to answer, but as you answer them, there’s a danger that you may not carefully exegete texts.
6. It can draw necessary and helpful conclusions from texts (or irresponsibly speculate).
Systematic theology is not always as simple as finding all of a topic’s relevant passages in Scripture, properly understanding their context, and then combining them. Systematic theology is not less than that, but it can be much more sophisticated than that. While it can draw conclusions that are necessary and helpful, it can also draw conclusions that are speculative or heretical. It can reach true and helpful conclusions, or false and dangerous ones.
7. It can efficiently assemble what the whole Bible teaches (but irresponsibly prooftext the Bible).
Systematic theology excels at efficiently assembling what the whole Bible teaches on a given topic. Bible teachers who go to places experiencing theological famine often immediately teach systematic theology because it is such an efficient way to communicate core Bible teachings. It can package what the whole Bible says in clear, organized, succinct ways which can make Bible doctrine easier to understand and easier to remember. On the other hand, systematic theology can flatten out the diverse emphases in the various parts of the Bible and be guilty of irresponsible prooftexting (citing a biblical passage to support a statement or doctrine.) Sometimes systematic theologians are guilty of plundering the Bible to support their theological system.
8. It can help you refute error (but it may be erroneous).
This is one way that systematic theology is a double-edged sword: it can help you quickly identify and refute error, but that depends on how good your systematic theology is. If your systematic theology is itself inaccurate, then it needs to be refuted! Assuming that your systematic theology is accurate, it is very helpful for identifying and avoiding false teachers, an essential task for pastors. who “must hold firm to the trustworthy word as taught, so that he may be able to give instruction in sound doctrine and also to rebuke those who contradict it” (Titus 1:9). All Christians need to know sound doctrine so well that they can deeply encourage others with it and refute those who oppose it. Sound systematic theology is indispensable for that, but only to the degree that it is accurate.
9. It can help you understand what the whole Bible teaches on a particular topic (but get distracted by related disciplines).
Some theologians are endlessly preoccupied with how other theologians have understood the Bible. While that may be interesting, it’s not systematic theology, but historical theology, a separate, though related discipline. Systematic theology works within the biblical text to see how the whole Bible coheres on a particular topic. When you do historical theology, you describe what others believed; when you do systematic theology, you build on historical theology and assert your own opinion.
10. It can help you do theological triage (but it does not automatically churn out the right answer).
Some Bible teachings are more important than others, and theological triage is the practice of determining the importance of any given doctrine within Christian theology. Paul writes in 1 Corinthians 15:3, “I delivered to you as of first importance what I also received.” If some matters were of first importance, other matters were of less importance. To simplify matters, we can think of three kinds or levels of Christian doctrine—issues that are foundational to the faith, issues that are necessary for denominational or local-church unity, and issues that are disputable and non-essential. Systematic theology can help you do theological triage, to discern what is first-, second-, or third-level doctrine. But the corresponding weakness for this strength is that systematic theology does not automatically churn out the right answer. Doing theological triage is not a science, but depends in part on your theological instincts. This helps explain why different Christians will do theological triage and come to different conclusions.
Systematic theology is a good gift and a helpful tool. We must do systematic theology. But as we do it, let’s do it responsibly—with an awareness of its strengths and dangers.
Where should you begin with systematic theology? Our favorite full-length treatment is Wayne Grudem’s Systematic Theology, which is written in such a way that it is suitable for any Christian reader. For a shorter treatment of the topic, consider J.I. Packer’s Concise Theology or Wayne Grudem’s Bible Doctrine, a condensed version of his larger work.