Since the very beginning of this blog, I’ve advocated that perhaps the common emphasis I see on having new believers read the New Testament is less than ideal. The argument I’ve heard is that the New Testament explains the basic theology that new Christians need. My response has always been two-fold. First, the New Testament is incredibly dependent on the Old Testament. Since the same God wrote both, the requisite theology for understanding the God of the New Testament is developed in the Old Testament. As a pastor recently tweeted:
https://platform.twitter.com/widgets.jsOnly 12 chapters in the New Testament don’t have a reference to the Old Testament.
— Matt Smethurst (@MattSmethurst) August 6, 2020
Twelve.
Now another response I want to develop today is that Christians learn basic theology just as much if not more from the Old Testament as from the New. In fact, the book of Isaiah covers almost any basic topic of Systematic Theology that a new believer would need to know.
For example, Isaiah is very thorough on the logical starting point of theology: theology proper. Isaiah is one of the richest portions in all Scripture on the doctrine of God. Isaiah 40–48 emphasizes the uniqueness of God against any other claim to deity. The section emphasizes God as creator and redeemer, as the comfort of his people. Isaiah 44:9–20 gives a scathing satire of idolaters that emphasizes the unique, spiritual nature of God. Throughout the whole book, God’s holiness (“The Holy One of Israel”) and sovereignty (“Yahweh of Hosts”) are emphasized.
Later portions of Isaiah introduce the Servant of Yahweh. While sometimes this title clearly applies to Israel, sometimes it clearly applies to Christ, and in doing so introduces the second person of the Trinity. (The Trinity, after all, is a doctrine you’re not likely to get a new believer to conclude on their own from Scripture.) We see the actions of Yahweh and his servant as redeemer, savior, and judge of all the nations of the world throughout the book.
Not only does Isaiah teach a theology of who God is, but Isaiah teaches at least one means of how to apply this doctrine of God: by trusting in Yahweh. Isaiah challenges first Ahaz (Isaiah 7) and later Hezekiah (Isaiah 36–39) to trust Yahweh in the face of life-threatening danger, and in so doing develops a theology of trust applicable to any Christian.
Isaiah also serves as an excellent introduction to bibliology. Isaiah 40 and Isaiah 55 emphasize the enduring and efficacious nature of the Word of the Lord. Once a new believer realizes that the “Word of Yahweh” is connected to “the Bible,” then the frequent special prophetic revelations to Isaiah each teach the new believer about the nature of the Scripture they now read.
Isaiah presents a Christian view of anthropology of hamartiology. Remember John Calvin’s famous line that the human heart is an “idol factory?” How can you hear this and not think of Isaiah’s mockery of the idol makers in Isaiah 43:9–20? Here people make idols out of things they find and make themselves, making God in their own image! By implication we are frequently pointed by Isaiah to remember that we are created in God’s image. The frequent statements of the wickedness of Israel and the nations, including hypocrisy (cf. Isa 64:6), give as thorough a picture of sin as any passage in the New Testament.
Isaiah has a particularly rich Christology. You absolutely cannot read the Servant songs, particularly Isaiah 53, or the Book of Immanuel (Isa 7–12) and not learn a huge amount about Jesus. You can’t read Isaiah and miss that God takes the One who knew no sin to be sin for his people. Isaiah will teach you about the Messiah, and unlike the New Testament, it will help you understand a longing and waiting for a future Messiah, teaching us to appreciate all the more that we now know Jesus personally.
Indeed, Isaiah teaches soteriology! Isaiah teaches that we are saved by Christ alone in Isaiah 53. Isaiah gives vivid pictures of God’s intention to save sinners, God’s comfort to save sinners, God’s redemption, as the basis of his people’s repentance. New believers may particularly think that their choice to believe the gospel is fundamental to their status now in Christ. Isaiah shatters this illusion. Isaiah frequently prophesies Israel’s future repentance, ultimately indicating that human repentance is God’s plan. God has foreordained repentance. Perhaps you might not learn the details of the differences between foreknowledge, election, and predestination from Isaiah, but from Isaiah you arrive at the reformed doctrine that God is the author of salvation who has preordained who will be reconciled to him in his people.
In laying out the future of the people of God, Isaiah points maybe not to ecclesiology (doctrine of the church), but to a more general doctrine of the people of God. In pointing to the restoration of Israel as God’s people as a spiritual restoration, Isaiah points to spiritual realities that are defining of the church today.
I think Isaiah even points to the ordinances we experiences as the means of grace in the church today. Isaiah refers to the cup of God’s wrath or fury causing people to stagger. What drink in the Old Testament causes people to stagger? As Jeremiah reminds us, the cup of the wine dregs of God’s wrath. What did Jesus ask to be taken from him at Gethsemane? The cup of God’s wrath. What was the cup he had just shared with his disciples? The wine representing his blood, shed to appease God’s wrath on their behalf. I believe this shared imagery of the cup is intentional.
Now Isaiah is extremely thorough in eschatology, a doctrine that we usually think of as unimportant to new believers, but a doctrine that is fundamental to understanding how we live the Christian life in expectant hope. Isaiah is littered throughout with prophecies of God’s future judgment and the restoration of all things in the New Creation, from Isaiah 2 straight through Isaiah 66. If you want to introduce a new believer to the future hope we have in Christ, little Scripture is as vivid as Isaiah in doing so.
All this to say, I think the natural plan of most Christians in my circles is to direct new believers to books like Romans or Ephesians or James or Philippians. And while all the Bible is God’s Word, and all of it is profitable, I do believe we could help new believers have a much stronger understanding of broader theology if we pointed them back to the Old Testament, even a hard book like Isaiah.
Now that’s just the objection: reading Isaiah is hard. But I answer this for you in three ways. (1) It’s not that hard. (2) We go to the moon not because it is easy, but because it is hard. Only lazy Christians shy away from reading and teaching the hard things. (3) We have so many resources to make it easy! Give a new Christian a Bible dictionary and a good study Bible, and Isaiah is eminently accessible! Sure, there will be confusing things, but all the Bible is confusing. Anyone who thinks that they’ve really understood all the major challenges of Philippians or the Gospel of Mark has really only done a shallow study. The Old Testament may seem slightly more foreign to 21st century protestants, but in reality it is God’s Word, and it will not return void. Isaiah 55:11 teaches me so!
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