“This is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people” (v. 33)
– Jeremiah 31:31–34
In our consideration of the Mosaic covenant as part of the overall covenant of grace, we were careful to note that one of the reasons God gave the law of Moses was to show His people beyond a shadow of a doubt their need for grace. If even those whom the Lord redeemed by grace from Egypt could not keep God’s law perfectly, then what hope does the rest of humanity have of rendering the perfect obedience God requires to be righteous before Him? By latching onto the law and using it to increase their sin, fallen people are shown their absolute need of the Lord’s gracious intervention to set things right (Rom. 7:7–25; Gal. 3:15–29). Sinners cannot in themselves be the seed of the woman who the Lord said would destroy sin and Satan (Gen. 3:15); their only hope is for a singular Seed to fulfill the covenant of grace. United to Him, they can share in His victory.
Christ is the fulfillment of the covenant of grace. He upholds the universe by the word of His power, fulfilling God’s promise to Noah to maintain the world as the arena for salvation (Gen. 8:22; Heb. 1:3). He takes on the curse for our breaking covenant with the Lord, fulfilling God’s promise to Abraham that He would deal with the consequences of our sin (Gen. 15; Mark 10:45). He obeys God’s law perfectly in our stead, doing what Adam should have done, so that we can be reckoned as righteous in Him, men and women who have fulfilled God’s will where both Adam and the collective nation of Israel failed (Gen. 3; Lev. 18:5; Matt. 4:1–11; Rom. 5:12–21). He is the Davidic king for whom God builds an everlasting house—the church triumphant, which inherits eternal life (2 Sam. 7:11; 1 Peter 2:4–5).
Today’s passage, one of the most important passages on the new covenant in Christ, which fulfills the covenant of grace, shows us what life under the fulfilled covenant looks like. Here we see clearly that the final aim of grace is not to set aside God’s law in every way. God’s saving grace is opposed to the law in the matter of justification—we are declared righteous by grace through the faith-imputation of Christ’s righteousness. But grace is not opposed to law in our sanctification. For by grace, God writes His law on our hearts, giving us the will to obey Him in order to thank Him for our great salvation, not to merit eternal life (Jer. 31:33). John Calvin comments, “The Gospel brings with it the grace of regeneration: its doctrine … penetrates into the heart and reforms all the inward faculties, so that obedience is rendered to the righteousness of God.”
The process of God’s writing His law on our hearts begins in this life but is not completed until our glorification. Christians grow slowly but surely in their willingness to obey and to repent for even the smallest sins, and at Christ’s return, the covenant of grace will be consummated in a new heaven and earth where righteousness dwells (2 Peter 3:13). Until then we pursue holiness, anticipating that great day to come.
Passages for Further Study
(Source: Devotional by Ligonier Ministries — the teaching fellowship of R.C. Sproul)