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Our Christian Terminology Is Built on the Old Testament

Key Words within the Christian Faith

Imagine approaching a non-Christian at a bus stop with this gospel presentation:

Did you know that you are a sinner in the eyes of our creator God, who is morally righteous but separated from you due to your unrighteousness? If you persist in transgressing his law, you face an eternity in hell on the last day of judgment. But the gospel is that you can have eternal life if you repent and put faith in Jesus, who atones for your sins and imputes his righteousness to you.

There is nothing inaccurate about these statements. But put yourself in the shoes of someone who has never read the Bible. Nearly half the words would make little to no sense: sinner, creator, righteous, unrighteousness, transgressing, law, eternity, hell, day of judgment, repent, faith, atone, and impute. A three-sentence gospel presentation—even the word gospel itself—presupposes a lot of information. This is one reason why evangelism in a post-Christian world may feel like explaining nuclear submarines to someone who has never seen the sea.

To make matters somewhat trickier, the NT rarely defines these words (with some exceptions, like 1 John 3:4). It just uses them. Why?

Old Made New

Greg Lanier

In Old Made New, Greg Lanier explains how New Testament authors used the Old Testament to communicate the gospel and present the person and work of Jesus. Writing for a broad range of readers, Lanier distills thorough research into descriptive examples and a simple 3-step study method.

When it comes to the nuts and bolts of the gospel, the NT often adopts essential concepts/words from the OT, particularly the Greek version.1 If we want to know what the key words above mean—not to mention others like sacrifice, impurity, guilt, holiness, condemnation, and so on—we have to open the OT to see how they are described. Knowing the OT at some basic level is essential to deciphering Christianese.

But the imprint of the OT on the gospel runs even deeper. I will outline how the NT authors regularly draw on the OT to explain the key steps or aspects of personal salvation.2

Personal Sin

Paul looks back on the fall of Adam to explain the state of mankind’s (original) sinfulness. He also looks to the OT to explain why each of us individually is guilty of our own (actual) sinfulness.3 And he piles it on to show that everyone is “under sin” (Rom. 3:9), citing six OT passages in Romans 3:10–18:

  • Ps. 14:1–3 (Rom. 3:10–12): No one does good or seeks God.
  • Ps. 5:9 (Rom. 3:13a): Our throats are open graves.
  • Ps. 140:3 (Rom. 3:13b): Venom is under our lips.
  • Ps. 10:7 (Rom. 3:14): Our mouths are full of cursing.
  • Isa. 59:7–8 (Rom. 3:15–17): Our paths are bloodshed and ruin.
  • Ps. 36:1 (Rom. 3:18): There is no fear of God before our eyes.

He even says, “as it is written,” only once (Rom. 3:10) to convey the singular voice of Scripture’s indictment against us. According to the OT, all of us are in bad shape, “so that every mouth may be stopped” from claiming otherwise (Rom. 3:19).

The OT, put differently, displays our personal need for the gospel.


Those who are dead in sin must be called to life. Without hearing the gospel, there is no ordinary means of salvation. Paul covers this truth in the back half of Romans 10, appealing to the OT through three sequential citations. He cites Isaiah 52:7 in Romans 10:15 to explain the necessity (and beauty) of issuing the gospel call. He goes on to Isaiah 53:1 in Romans 10:16 to remind us how Isaiah, too, brought a report of “good news” to Israel. And he lands on Psalm 19:4 in Romans 10:18, reflecting on how the “ends of the world” have heard the “voice” of good news.

Merely hearing the “call” does not make you saved, for the good news can fall on deaf ears today just as much as in OT Israel. But it is a prerequisite nonetheless. To believe, one must hear the call (Rom. 10:14).


The regenerated heart responds to the call of God in a twofold manner, collectively called “conversion”: repenting of sin and placing faith in Christ.

Jesus points to the OT to express the necessity of repentance in his parable of the rich man and Lazarus (Luke 16:19–31). In the parable, a man faces eternal punishment and pleads with Abraham to warn his brothers so that they might repent and avoid a similar fate (Luke 16:30). But Abraham (giving voice to Jesus’s perspective in the parable) pushes back, saying that they already have “Moses and the Prophets” (Luke 16:29, 31)—what more do they need? Interestingly, Jesus does not cite, quote, or allude to a specific passage. Rather, this general reference suggests that the entire OT preaches the message of repentance.

Turning to faith, we see a similar general reference by Peter to “all the prophets” in Acts 10:43, who “bear witness that everyone who believes” will be forgiven and saved. He does not say where this is written in the OT prophets, only that “all” of them convey this truth. But other NT writings pinpoint concrete OT passages that emphasize personal faith: Deuteronomy 30:12–13 (Rom. 10:6–8), Isaiah 28:16 (Rom. 9:33; 10:11; 1 Pet. 2:6–8), Joel 2:32 (Acts 2:21; Rom. 10:13), and Habakkuk. 2:4 (Rom. 1:17; Gal. 3:11).

It is striking that the NT does not treat the OT as offering legalism as the path to God but, rather, finds support for a unified message: repent and believe.


In many respects the centerpiece of the gospel (in its personal dimension) is justification: when God pronounces a sentence of “not guilty” over you and declares you righteous in his sight.4 For this doctrine, the OT is particularly important. We will drill down on two key passages used by Paul in articulating what justification means.

First, Paul draws on Genesis 15:6 in Romans 4:3 and Galatians 3:6 as the touchstone for justification.5

Second, Paul cites Psalm 32:1–2 in Romans 4:6–8 to elaborate on justification: “just as David also speaks of the blessing of the one to whom God counts righteousness apart from works: ‘Blessed are those whose lawless deeds are forgiven, / and whose sins are covered; / blessed is the man against whom the Lord will not count his sin.’”

This passage is linked to Gen. 15:6 through the use of the same word for “count,” underlined above (logizomai). Thus, the psalm helps round out the logic of justification:

  • Abraham’s example defines things positively: justification = God “counts” you righteous.
  • Psalm 32 defines things negatively: justification = God “does not count” you unrighteous but forgives your sins.

Justification is a two-sided coin.6

Yet the context of Psalm 32 adds further color. David describes groaning all day under the guilt of sin, feeling God’s heavy hand of discipline (Ps. 32:3–4). But he pivots to hope, knowing that if he confesses and repents, he will receive forgiveness (32:5). The one who, then, has been made right with God shouts for joy (32:11).

A three-sentence gospel presentation—even the word gospel itself—presupposes a lot of information.


After you become a Christian—regenerated, justified (by faith), and adopted—you are called into a life of sanctification.7 There is both an initial and ongoing element of sanctification. You are set apart by God from the world (positional or definitive sanctification; see 1 Cor. 1:2; 6:11; 2 Tim. 2:21) and drawn into an ongoing pursuit of holy living (progressive or active sanctification; see Rom. 6:22; 1 Thess. 4:3–7).8 There are numerous ways sanctification is pictured in the NT (e.g., the metaphors of walking and fruit-bearing), but one of the more striking is the use of Leviticus by Jesus and Peter.

Leviticus 11:44 gives a classic expression of the sanctification God expects: “Consecrate yourselves therefore, and be holy, for I am holy” (cf. Lev. 19:2; 20:7). Our behavior (“be holy”) is to be patterned after the God who has set us apart.

Rather than shying away from this bold statement out of fear that it is overly legalistic, Jesus and Peter put it to direct use. At a key point of his Sermon on the Mount, Jesus alludes to it (changing “holy” to “perfect”), saying, “You therefore must be perfect, as your heavenly Father is perfect” (Matt. 5:48).9 This command sums up the guidance Jesus gives his disciples pertaining to murder/anger, adultery/lust, divorce, oaths, revenge, and loving enemies (Matt. 5:21–47). Peter follows suit, instructing his readers that, as “obedient children” (note the adoption theme), they must abstain from sinful passions and “be holy in all your conduct” (1 Pet. 1:15). By what authority does Peter press this home? Not his own, but what is “written” in Leviticus 11:44, which he cites directly in 1 Peter 1:16.

The OT provides stimuli for sanctified living as a Christian.


Previously, I described how Paul uses Isaiah to describe where all this is heading from a big-picture historical perspective. What about the individual perspective? Christianity emphasizes that the righteous will be resurrected unto glory. Classic statements of glorification are Romans 8:17, 8:30, and Philippians 3:20–21. But elsewhere Paul puts the finishing touches on his elaborate description of future bodily resurrection in 1 Corinthians 15 by quoting Isaiah 25:8 and Hosea 13:14.

Paul’s use of Isaiah and Hosea to describe the defeat of death in resurrection is an appropriate capstone to our discussion of personal salvation. It links that individual reality—glorification after death—with God’s work in history. God’s plan heads toward a great wedding feast, where individual resurrected saints will dine together with him!


When the gospel of Christ becomes yours and lifts you out of sin, many blessings come with it, ranging from regeneration to justification to glorification. One of the key ways the NT authors use the OT is to explain these truths. Not only does the OT announce the historical plan of salvation, but it also bears witness to how it becomes personally yours by faith.


  1. Karen H. Jobes and Moisés Silva, Introduction to the Septuagint, 2nd ed. (Grand Rapids, MI: Baker Academic, 2015), 200–205.
  2. For a classic treatment of the ordo salutis (“order of salvation”) presented here, see John Murray, Redemption Accomplished and Applied (Grand Rapids, MI: Eerdmans, 1955).
  3. On distinguishing “original” and “actual” sin, see Westminster Confession of Faith 6.4
  4. For an extensive treatment of the doctrine, see Matthew Barrett, ed., The Doctrine on Which the Church Stands or Falls: Justification in Biblical, Theological, Historical, and Pastoral Perspective (Wheaton, IL: Crossway, 2019).
  5. See Benjamin Schliesser, Abraham’s Faith in Romans 4: Paul’s Concept of Faith in Light of the History of Reception of Genesis 15:6 (Tübingen: Mohr Siebeck, 2005).
  6. Along these lines, the Westminster Shorter Catechism defines justification as God “pardoneth all our sins, and accepteth us as righteous in his sight” (question 33).
  7. See R. Michael Allen, Sanctification (Grand Rapids, MI: Zondervan, 2017).
  8. Ben Dunson, “Biblical Words and Theological Meanings: Sanctification as Consecration for Transformation,” Themelios 44, no. 1 (2019): 70–88.
  9. The word translated “perfect” (teleios) conveys the sense of being “whole” or “mature.”

This article is adapted from Old Made New: A Guide to the New Testament Use of the Old Testament by Greg Lanier.

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