Why Every Preacher Needs Systematic Theology – Part 2

Recently I came across a definition of systematic theology as “keeping the whole Bible in view when reading any verse.” I find that definition helpful for two reasons. First, because it emphasizes how all the parts of Scripture work together to help us understand the main truths. And second, because it reminds us that the Bible is the epistemological foundation of our system. We should not impose extra-biblical ideas onto Scripture, but we should compare Scripture with Scripture and allow the whole counsel of God to form our theology. And, though we need to be careful that we don’t force a passage into an artificial mold, we need to understand each particular passage in balance with the rest of biblical revelation.

In the previous article, we began discussing the importance of systematic theology for good preaching by defining it and describing healthy and unhealthy ways it affects our interpretation of Scripture. As defined in that article, systematic theology is the practice of ordering biblical truths by subject or by theme. This definition and the one in the previous paragraph both emphasize the way the “big picture” helps us interpret individual passages correctly.

And that’s what we’re really about—getting the meaning right. Few Christians deliberately misinterpret the Bible, but this happens inevitably when they are unfamiliar with big biblical themes. We won’t put the puzzle pieces together correctly when we don’t know where they fit in the larger picture. Systematic theology is a way of checking the piece in our hands against the macro picture.

But I want to think specifically about how good systematic theology improves the quality of preaching by looking at two benefits:

1. Systematic theology protects from error.
2. Systematic theology promotes correct interpretation.

Systematic Theology Protects from Error

Good exegesis is hard work. Correctly interpreting a verse or passage requires studying logical arguments, key words, context, history and audience, and a smattering of other details. And even if we get all this right, it is possible to misinterpret the text by zooming in so closely that we lose its place in the broader biblical picture. We can deduce something from one text that contradicts the clear teaching of another passage, and as a result preach something untrue.

How does the preacher—or any other student of Scripture—keep from misinterpreting texts? Systematic theology provides a kind of shortcut. It summarizes answers to big questions like: 

• What is God like?
• What does God love?
• What does God hate?
• Who is man?
• What is sin?
• What are the consequences of sin?
• How can we be saved from these consequences?
• How does God want us to live?
• What are God’s final plans for His creation?

Asking and answering these questions is a form of systematic theology. By giving clear, accessible answers to these questions, systematic theology helps us keep the whole Bible in view when interpreting a particular passage. It helps us interpret the pieces in keeping with the whole.

This is important for preachers because they of all people need to teach the Bible clearly and accurately. More than once I have heard a pastor boldly preach a point that seemed obvious in a text but that actually contradicted another text. His failure to check his conclusions against the rest of Scripture left him vulnerable to unbiblical ideas. As a result, he proclaimed something as God’s truth though it contradicted something clearly revealed elsewhere in God’s Word.

I don’t mean to imply that Scripture contradicts itself. Rather, I’m saying that many passages can be legitimately interpreted in more than one way based on their words and grammar, and we need to compare any text with the rest of Scripture to know which possible interpretations are permissible. We are led to the right interpretation by comparing the text in question with other related texts. When we fail to do this we may preach an idea that is alien to or even contrary to Scripture.

In short, we need to check any specific text against the broader biblical evidence, ensuring that we don’t preach from one text what is negated in another.

Systematic Theology Promotes Correct Interpretation

The previous section talks about moving from a specific text to broader themes. We should also be aware of how our understanding of broad biblical themes helps us understand the meaning of specific texts. Systematic theology promotes correct interpretation by giving us a general framework that helps us understand a particular text. Anytime we read a verse or passage, we bring our collected knowledge of the rest of the Bible. That general knowledge helps us see the point of particular passages.

Though we need to be careful not to miss the particular emphasis of a passage in question, we are often helped if we are acquainted with other passages that teach similar ideas. If our presuppositions are formed by other Scriptures, and not merely by tradition, philosophy, or experience, we get a bit of a jump start to our interpretation. Being familiar with the main doctrines of Scripture helps us get to the heart of a particular passage.

Systematic Theology in Action

Let’s explore the interplay between systematic theology and exegesis with an example. A common mistake I see in our preaching is isolating obedience texts from texts which explain how obedience is possible. Command texts are isolated from means texts. Indicative texts (what is objectively true because of who God is and what He has done) are isolated from imperative texts (what we are to do in response to who God is and what He has done).

Perhaps the most common example is the tendency to isolate the Sermon on the Mount from the rest of Jesus’ teachings, turning it into a New Testament law which we obey in order to win God’s favor. These commands are taken as directives which we obey in order to please God and thereby save ourselves from eternal judgment. But the Bible is clear that we cannot keep the law perfectly. A friend of mine observed that if we try to obey the Sermon on the Mount as a way to save ourselves, all we get is Israel 2.0. They failed to keep the law and were judged by God and exiled from the promised land. Likewise, unless we conform perfectly to the law, we stand condemned. As James says in his letter, “Whoever shall keep the whole law, and yet stumble in one point, he is guilty of all” (James 2:10). The apostle Paul teaches in Romans that the Jews who have the law are still condemned because they do not keep the law.

Should Christians seek to follow the Sermon on the Mount? Absolutely! It stands as the greatest sermon of all time, upholding the greatest moral standard found, not only in Scripture, but in all ancient and modern religious writings. The question is not about whether Christians should obey Jesus’ commands. Instead, the question is, “How do we obey?”

But first of all, we need to know that Scripture does indeed teach that God’s children can live lives that please Him. Not savingly, not so that we are justified (or retain our justified status), but because we are justified. God’s children will want to obey Him, and Scripture assumes that we will obey sufficiently that God is pleased with our obedience. Paul prays for the believers in Colosse that they would “walk worthy of the Lord, fully pleasing Him.” (Col 1:10). We’re not talking of some sort of Christian perfectionism here, or Keswick second blessing. Paul is not implying that perfect obedience is necessary for God to be pleased, any more than a child must perform perfectly in order to win the smile of his father or mother. God’s children should live to please Him.

Let’s return to the question we’re considering. “How do we obey God?” Perhaps we just determine to try our hardest, and God accepts our efforts because they are sincere. Do we have the ability within ourselves to please God?

In Romans 8:8 (a part of a longer treatment by the apostle Paul on this very subject), we find that “those who are in the flesh cannot please God.” That “cannot” is weighty. It is an absolute exclusion of any ability to do, on our own, acts that God approves of. Any command which is obeyed “in the flesh” is not pleasing to God.

This is echoed many other times in the New Testament. Jesus said, “As the branch cannot bear fruit of itself, unless it abides in the vine, neither can you, unless you abide in me…Without Me you can do nothing” (John 15:4-5). On our own, we are incapable of bearing fruit. We are incapable of obeying God’s commands in a way that pleases Him.

On the one hand, Paul says that we should want to please God—and implies that we will be able to. Yet on the other he says that we cannot please God on our own. How do these come together? How do we live lives that please God?

Paul answers this in the following verses in Romans 8. If we are in Christ, “we are not in the flesh but in the Spirit.” The Holy Spirit is in us—and we are in Him—and He gives us the ability to obey God’s commands. As verse 11 says, “He who raised Christ from the dead will also give life to your mortal bodies through His Spirit who dwells in you.” That this is talking about the current experience of believers and not of future glorification is clear because Paul speaks of our current “mortal bodies” and because he says the Spirit “dwells” in you, not that the Spirit “will dwell.” He is talking about our present experience of the power of the Spirit to help us overcome sin.

In a similar vein, Paul is astounded that the Galatians are trying to be sanctified by their own effort. They couldn’t even believe the gospel on their own, and now they are trying to live obedient lives on their own. “Having begun in the Spirit, are you now being made perfect by the flesh?” Of course not! It’s the One who began the good work who continues it and will complete it (cf. Phil 1).

Jesus has the same thing in mind in John 15, though He uses different terms. As we saw earlier, Jesus taught that we cannot bear good spiritual fruit on our own: “Without Me you can do nothing.” But when we are united to Christ by faith, and the Spirit lives in us, we will bear fruit. “He who abides in Me, and I in him, bears much fruit” (John 15:5). When God is in us by His Spirit, His character begins to flow out of us. He enables our obedience.

We are supposed to please God. We are supposed to obey Him. But we can’t do that on our own. The Bible says that the Spirit helps us do what we ought to do. This is a basic theological principle. For our obedience to God’s commands to please Him, we must be enabled by God’s Spirit.

We find this principle consistently taught throughout Scripture. When left to our own, we cannot please God. We need God’s help to live up to God’s standards. This is, I believe, a fundamental theological principle, one that should constantly be in our minds when we study God’s word.

We should always be aware of this basic principle when studying and preaching a particular text. Especially when we encounter a command text, we should ask, “How do I preach this in a way that promotes grace-based, Spirit-empowered obedience rather than works-based, man-empowered moralism?” Preaching obedience to God’s commands by naked human effort undermines the gospel.

So many Mennonite sermons fall flat on this very point. The preacher correctly exegetes the imperatives of the text, but he implicitly or explicitly communicates that we are supposed to obey God’s commands by our own power. It’s akin to ordering a stalled car to move when there’s no gas in the tank. I absolutely believe the Bible makes demands on our lives. God expects us to obey Him. But we need not only to communicate what God wants but also how obedience is possible. We do preach command texts, and the necessity of obedience (cf. Heb. 12:14). But we dare not preach these as commands which we obey by our own effort in order to earn God’s favor. Instead, based on Romans 8, John 15, and other similar texts, we need to preach grace-motivated, Spirit-empowered obedience.

Conclusion

This is one example of many of why systematic theology is necessary for preaching to be true to the Bible and effective in the lives of God’s people. When the preacher doesn’t understand broad biblical themes, his preaching misses the mark because he ends up preaching extra-biblical or even contra-biblical ideas.

One way to improve your understanding of biblical themes is to pick up a systematic theology such as Introduction to Theology by J. C. Wenger (available through the S&T bookstore). There are plenty of good systematic theology volumes by conservative evangelicals that we can benefit from even if we don’t agree with them on everything.

Even better, read the Bible intentionally, with your brain on. Ask questions, then ask more questions, then ask more questions. John MacArthur, a lifelong expositor, says that asking questions is a central part of his study process. He asks questions of his text and searches for answers until he doesn’t have any questions left. Asking questions gets you to the heart of a text, and it leads you into other related texts that touch on related issues or provide information that is lacking in your initial text. This is one way to immerse yourself in Scripture; continual immersion in Scripture is the best way to develop a familiarity with core theological truths.

As I said in the first article, we need to be aware of how our theological systems are affecting our interpretation of Scripture. Faulty presuppositions can be one of the greatest barriers to getting the text right. On the other hand, presuppositions which are shaped by Scripture are vital to good exegesis of any given passage. And not only to exegesis, but also to the preaching which proclaims that text. Good systematic theology is essential to faithful, effective preaching.