How to Understand and Apply the Old Testament: Part 1

Series: How to Understand and Apply the Old Testament 

by Jason DeRouchie September 10, 2020


An Introductory Journey of Discovery and Encounter


“The good hand of his God was on him. For Ezra had set his heart to study the Law of the LORD, and to do it and to teach his statutes and rules in Israel” — Ezra 7:9–10

In this blog series, we embark on a journey of discovery and divine encounter. What we call the Old Testament (OT) was the only Bible that Jesus had. Books like Genesis and Deuteronomy, Isaiah and Psalms guided his life and ministry as the Jewish Messiah. It was these “Scriptures” that Jesus identified as God’s word (Mark 7:13; 12:36), considered to be authoritative (Matt 4:3–4, 7, 10; 23:1–3), and called people to know and believe in order to guard against doctrinal error and hell (Mark 12:24; Luke 16:28–31; 24:25; John 5:46–47). Jesus was convinced that what is now the initial three-fourths of our Christian Bible “cannot be broken” (John 10:35).[1] He was also certain that the OT bore witness about him (Luke 24:27, 46; John 5:39, 46), that he would completely fulfill it (Matt 5:17–18; Luke 24:44), and that it called for repentance and forgiveness of sins to be proclaimed in his name to all nations (Luke 24:47). I love the OT because of the way it portrays God’s character and serves as a witness to the majesty of our Messiah. The OT is the initial three-fourths of God’s special revelation to us, and I want you to interpret the OT rightly because there is no higher need for mankind than to see and celebrate the sovereign, savior, and satisfier disclosed in its pages.  

The Interpretive Task

The blog posts in this For the Church series are shortened forms of the chapters in my book, How to Understand and Apply the Old Testament. [2] I wrote this study to guide Christians in interpreting the OT. The process of biblical interpretation includes both exegesis and theology. The former focuses mostly on analysis, whereas the latter addresses synthesis and significance.[3] Narrowly defined, exegesis of Scripture is the personal discovery of what the biblical authors intended their texts to mean, as they were “carried along by the Holy Spirit” (2 Pet 1:21). Exegesis is about discovering what is there in the text. Theology is the process of thinking and studying about God. Because Scripture is God’s word for all time and because every biblical passage has a broader context (historical, literary, and biblical), exegesis (narrowly defined) naturally moves us into various theological disciplines:

•  Biblical theology considers how God’s word interconnects and climaxes in Christ.

•  Systematic theology examines what the Bible teaches about certain theological topics.

•  Practical theology details how the Christian should respond to the Bible’s truths.

Biblical interpretation is not complete until it gives rise to application through a life of worship. Exegesis moves to theology, and the whole process is to result in a personal encounter with the living God disclosed in Scripture. Doxology––the practice of glorifying or praising God––should color all biblical study. 

Presuppositions that Guide Biblical Interpretation

Before explaining the process of biblical interpretation, I should first mention some presuppositions that guide my approach.

1. Biblical interpretation necessitates that we view Scripture as God’s word.

The only way to truly fully grasp what the biblical authors intended is to believe (like they did) that they were reading and writing God’s very word (Isa 8:20; 1 Cor 14:37). That Scripture is God’s word requires us to have a submissive disposition. We must be willing to let our understanding and application of truth be conformed to the Bible’s declarations, all in accordance with God’s revealed intention. The Bible is special revelation––God’s disclosure of himself and his will in a way we can understand (1 Cor 14:37; 2 Tim 3:16; 2 Pet 1:20–21). The very words, and not just the ideas, are God-inspired (Matt 5:17–18; 1 Cor 2:13; 2 Tim 3:16–17). All of the above implies that the Bible is both infallible—a sure and safe guide in all matters of faith—and inerrant—entirely true and trustworthy in all matters of fact that the biblical authors intended to convey. The key for us is that the Bible will never lead us astray and should bear the highest influence in our lives.

2. Biblical interpretation assumes that Scripture’s truths are knowable.

In addition to being true, God’s word is also knowable. Proper understanding of Scripture assumes that the Bible is, by nature, clear in what it teaches and that humans can know truth. Peter recognized that “there are some things in [Paul’s letters] that are hard to understand,” but he went on to say that it is “the ignorant and unstable” who “twist” these words “to their own destruction, as they do the other Scriptures” (2 Pet 3:16). The anointed psalmist was convinced that God’s word enlightens our path and imparts understanding (Ps 119:105, 130). Paul wrote his words plainly (2 Cor 1:13) and called others to “think over” what he said, trusting that “the Lord will give you understanding in everything” (2 Tim 2:7).

3. Biblical interpretation requires that we respond appropriately in God-dependence.

Having discovered what God has spoken, we must then move on to recognize that his word requires us to obey him (2 Tim 3:16). We thus pray I.O.U.S.:[4] “Incline [our] heart[s] to your testimonies” (Ps 119:36). “Open [our] eyes that [we] may behold wonderful things in your law” (119:18). “Unite [our] heart[s] to fear your name” (86:11). And “satisfy us in the morning with your steadfast love, that we may rejoice and be glad all our days” (90:14). Heeding God’s word as he expects can only come about by God’s grace in Jesus (1 Cor 2:14). Only in Christ is the veil of hardness toward God’s word taken away (2 Cor 3:14), but in Christ, the word becomes near us, in our mouth and in our heart (Rom 10:8). The biblical authors’ ultimate intent included a transformed life, the foundation of which is a personal encounter with the living God. We will not meet God in this way apart from his help.

Reasons the OT Is Important for Christians

If Christians are part of the new covenant, why should we seek to understand and apply the OT? While much more could be said, I will briefly give some reasons here why the first word in the phrase Old Testament must not mean unimportant or insignificant to Christians.

To begin, the OT was Jesus’s only Scripture and makes up three-fourths (75.55%) of our Christian Bible. If space says anything, the OT matters to God, who gave us his word in a book. Besides being large, the OT substantially influences our understanding of key biblical teachings like God’s kingdom and covenants, creation and judgment, temple and missions, God’s people and land. Indeed, the NT’s entire worldview and instruction are built upon the framework the OT supplies. And since the OT and NT are so interconnected, we meet the same God in both Testaments (Heb 1:1). 

Besides the above, the OT promises the very gospel concerning the Son that we now celebrate (Luke 4:16–21; Acts 13:32; Rom 1:1–3; Gal 3:8; 1 Pet 1:10–12; cf. Isa 40:9–11; 52:7–10; 61:1). The OT bears a deep connection to Jesus, who did not come to destroy the old covenant law, but to fulfill it (Matt 5:17–20). Thus, the OT itself maintains lasting relevance for us in the way it displays God’s character (Rom 7:12), points to Christ’s excellencies (John 1:45; 5:39; Acts 10:43), and portrays for us the scope of love in all its facets (Deut 6:5; 10:19; Matt 22:37–40; Rom 13:8–10). The OT is also important because Jesus said that all of the OT points to him, foretells his death and resurrection, and anticipates the worldwide mission his life would generate (Luke 24:27, 47; cf. Acts 3:18; 26:22–23). If you want to know Jesus more, read the OT! 

Because the OT is about Jesus, the NT writers even stress that God gave the OT specifically for Christians (Rom 15:4; 1 Cor 10:11; 1 Pet 1:12). The OT is sufficient to make people wise for salvation in Christ Jesus (2 Tim 3:15), and for this reason Paul encouraged Timothy to preach the OT (4:2–4). While we now have the NT, we can, and indeed must, appropriate the OT like Jesus and his apostles did for the good of God’s church.

Overview of the Interpretive Process: T.O.C.M.A.

As I mentioned prior, this blog series consists of adaptations from my book, How to Understand and Apply the Old Testament. These blog posts will summarize in a brief and easy to understand way a twelve-step process to interpret Scripture. I abbreviate the process as TOCMA, which stands for Text, Observation, Context, Meaning, Application. I will give one blog post to each of the twelve steps. 

Text—What is the makeup of the passage?

  • Genre: Determine the literary form, subject matter, and function of the passage, compare it to similar genres, and consider the implications for interpretation.
  • Literary units and text-hierarchy: Determine the limits and basic structure of the passage.
  • Text-criticism: Establish the passage’s original wording.
  • Translation: Translate the text and compare other translations.

Observation—How is the passage communicated?

  • Clause and text grammar: Assess the makeup and relationship of words, phrases, clauses, and larger text-units.
  • Argument-tracing: Finish tracing the literary argument and create a message-driven outline that ties to the passage’s main point.
  • Word and concept studies: Clarify the meaning of key words, phrases, and concepts.

Context—Where does the passage fit?

  • Historical context: Understand the historical situation from which the author composed the text and identify any historical details that the author mentions or assumes.
  • Literary context: Comprehend the role the passage plays in the whole book.

Meaning—What does this passage mean?

  • Biblical theology: Consider how your passage connects to the Bible’s overall flow and message and points to Christ.
  • Systematic theology: Discern how your passage theologically coheres with the whole Bible, assessing key doctrines especially in direct relation to the gospel.

Application—Why does this passage matter?

  • Practical theology: Apply the text to yourself, the church, and the world, stressing the centrality of Christ and the hope of the gospel.

Come with me on this journey of discovery and skill development. The following nine posts focus especially on the process of exegesis, whereas the final three posts will address theology. God-honoring worship is both the fuel and goal of every stage of biblical interpretation. So may your study result in practice and overflow in teaching that is filled with praise and proclamation––all for the glory of Christ and the good of his church among the nations.


[1] Unless otherwise noted, all English translations within the body-text of these blog posts are from The Holy Bible, English Standard Version, copyright © 2011 by Crossway Bibles, a division of Good New Publishers.

[2] Jason S. DeRouchie, How to Understand and Apply the Old Testament: Twelve Steps from Exegesis to Theology (Phillipsburg, NJ: P&R Publishing, 2017).

[3] For these distinctions, see Andrew David Naselli, “D. A. Carson’s Theological Method,” SBET 29.2 (2011): 256–72.

[4] John Piper, When I Don’t Desire God: How to Fight for Joy (Wheaton, IL: Crossway, 2004), 151.