This is part of a commentary series through the Book of Galatians. It began with Galatians 3:1-6. This series will progress until the book is finished, then circle back and cover ch. 1-2. This article covers Galatians 3:15-22.
Paul has spoken about the right way to understand the Mosaic Law. Now, he presses the point home with an analogy about Abraham.
Brothers and sisters, let me take an example from everyday life. Just as no one can set aside or add to a human covenant that has been duly established, so it is in this case (Galatians 3:15).Galatians 3:15
Sometimes it’s helpful to put things in everyday terms. Suppose you have a contract or some other legal arrangement. We all know that, once the signatures are on the dotted line, then the deed is done. It’s sealed. You can’t add to or delete anything. It is what it is. Well, Paul says, it’s the same in this case with God and His arrangements with us!
“How so?” you ask. Paul answers …
The promises were spoken to Abraham and to his seed. Scripture does not say “and to seeds,” meaning many people, but “and to your seed,” meaning one person, who is Christ.Galatians 3:16, quoting Genesis 12:7; 13:15; 24:7
God made a promise—an irrevocable contract—with Abraham and his descendant. But Paul points out something pretty curious. The promise was to Abraham and his descendant—singular. It wasn’t to all Abraham’s offspring, but to one descendant in particular, who is Christ.
What does this mean?
If you’re a believer, then you’re metaphysically fused with Christ—made one with Him on an invisible level. Your bible translation probably has the phrase “in Christ” a lot in Paul’s letters, because it’s one of his favorite expressions. We’re “baptized into Christ,” “buried with Him through baptism into death,” “crucified with Him,” and “alive to God in Christ Jesus,” (Rom 6:1-11). All this language is expressing that, when we trust in Jesus, we’re made one with him in an unseen way. Perhaps the closest thing I can compare it to is a marriage; there’s a oneness that happens in marriage that’s unseen, hidden, but very real. What Paul is saying is these promises were to Abraham and His crowning descendent, Jesus—along with everyone else who has been made one with Him (see Gal 3:29).
God made several promises to Abraham (see Genesis 22:17-18), and all of them are fulfilled through Christ—including the promise of the land. Paul wrote, “Scripture does not say ‘and to seeds,’ meaning many people, but ‘and to your seed,’ meaning one person, who is Christ,” (Galatians 3:16). This “and to your seed” quotation is from the Greek version of Genesis 17:8, which refers to that land promise. Paul is saying that all the promises to Abraham—even the one about “the whole land of Canaan” (Gen 17:8)—are fulfilled by Christ as the representative son of Abraham (Mt 1:1).
This suggests that Abraham and his physical descendants are a foreshadowing of Jesus and His spiritual brethren. If so, then we can understand all the precious promises to Abraham as shadows of a greater fulfillment—maybe something like this:
So, back to the point.
Paul is saying that, if God made unbreakable promises to Abraham and his descendant—a promise based on faith and trust—then God certainly hasn’t changed the terms of the promise later on. “It was not through the law that Abraham and his offspring (singular—Jesus) received the promise that he would be heir of the world, but through the righteousness that comes by faith,” (Romans 4:13). So, the Judaizers who are peddling the “work to earn your salvation” message are wrong. They have to be wrong. If they’re right, then God changed the terms of the agreement.
Darth Vader once said, “I’m altering the deal! Pray I don’t alter it any further …” Well, God doesn’t alter deals. Unlike Vader, he’s trustworthy.
What I mean is this: The law, introduced 430 years later, does not set aside the covenant previously established by God and thus do away with the promise. For if the inheritance depends on the law, then it no longer depends on the promise; but God in his grace gave it to Abraham through a promise.Galatians 3:17-18
The Mosaic law didn’t change the terms of the deal. If we have faith like Abraham, then we’re children according to the promise. Things didn’t change at Mt. Sinai. Instead, it’s the wrong ideas of relationship with God that has warped the common understanding of the Mosaic law by Jesus’ day, and Paul’s, too. Inheritance of the promise isn’t based on effort, but on faith.
Why, then, was the law given at all?Galatians 3:19
That’s a fair question. If the Mosaic law was never a vehicle for salvation, then what was it?
It was added because of transgressions until the Seed to whom the promise referred had come.Galatians 3:19
Notice that all the promises to Abraham are summed up as one package (“the promise”—singular), and that Paul attributes this whole bundle to one representative “seed”—Jesus (see the same at Romans 4:13). The Mosaic Law was a tool to hem us in until Christ would come. It told us how to live, how to act, how to maintain loving relationship with God and with each other. It told us how to be God’s people, for a particular time in a particular place, until Christ would arrive on the scene. Picture God’s people from the Exodus to Pentecost as being in a plane, circling the airport, waiting on clearance to land. They know they’ll land, but they aren’t yet there.
So, God told us how to live until He “landed the plane.” We break the law, we feel guilt, we confess our sin and perform the ritual to atone for that sin. We go on. It’s in this way that the Mosaic law “hems us in” and keeps us on the right track, until the Messiah arrives in the First Advent.
The law was given through angels and entrusted to a mediator. A mediator, however, implies more than one party; but God is one.Galatians 3:19-20
The Mosaic law was entrusted to a mediator—Moses. But this new arrangement, this new covenant, is different. Now, there’s only one party. God Himself makes the contract and obligates Himself to carry it out. There is a straight line starting from (1) when God chose His people by promise with Abraham, (2) connecting right to His promise to David of a perfect king, and from there (3) on to God’s pledge of perfect peace through a new and better arrangement. Along this track, the Mosaic law is just a guardrail keeping us on the trail. It isn’t a different trail at all.
Is the law, therefore, opposed to the promises of God? Absolutely not! For if a law had been given that could impart life, then righteousness would certainly have come by the law. But Scripture has locked up everything under the control of sin, so that what was promised, being given through faith in Jesus Christ, might be given to those who believe.Galatians 3:21-22
So, then, what does the Law have to do with God’s promises to Abraham? Well, first, if righteousness could have come by way of following the law, then it would have (cf. Gal 2:21). But, in the second place—and here is the crux of it all—the Mosaic law showed us our sin, reminded us of it all the time, so that we’d be ever more ready to embrace the permanent solution Christ offered when He came.
Paul uses a strange phrase. He says the Scripture “locked up everything under the control of sin,” (Gal 3:22). He seems to mean that, although it’s theoretically possible that a perfect person could come along, obey the law in every respect, and receive righteousness as a reward—it’ll never happen. Why not? Because Scripture (the entire Old Covenant canon) shows us we’re not that good. We never will be. It shows us that everything is “locked up” under sin’s power. The original imagery is that of a school of fish swept up in a fisherman’s net—caught! We’re all trapped, as if the door of a great dungeon has swung shut on us. So, that “perfect person” won’t ever come along in this world … unless that person comes from outside the bubble.
When we see God’s rules, then consider our own constant failure to live up to them, then we’re driven to put faith and trust in the promised Savior—the One who loved God perfectly and obeyed the law completely, in our place, as our substitute. That dungeon swings shut … but why? “So that what was promised, being given through faith in Jesus Christ, might be given to those who believe,” (Gal 3:22). “It was to make them understand their real inner life, their alienation from himself, and their need of his grace.”
All those promises to Abraham—which Paul once more sums up as one bundle of blessings (“what was promised”)—are given to those who believe and have faith in Jesus Christ. Once more Abraham, his physical descendants, and the literal promises in the land corresponded to and prefigured something much better.
That was the Law’s purpose. It wasn’t a vehicle for salvation. It was tool to make us look forward to the Messiah so Abraham’s offspring—the true offspring (cf. Luke 3:8)—would recognize Him when He came.
 The Greek word here is the same one we often translate as “covenant,” and some translators assume Paul is referring to a will. It doesn’t matter—Paul just wants you to imagine a legal contract in your mind.
 See especially Thomas R. Schreiner, Galatians, in ZECNT (Grand Rapids: Zondervan, 2010), at Galatians 3:16a-d.
“… if the blessing promise includes a reconstituting of the “seed” with a global identity in Christ, then one should be cautious to separate the land promise from this same transformation. Indeed, within the argument of Galatians 3, the eschatological fulfillment of the land promise appears to stand behind Paul’s argument,” (Jason DeRouchie, “Counting Stars With Abraham And The Prophets: New Covenant Ecclesiology In OT Perspective, in JETS 58:3 (Sep 2015), p. 480)
 For the typological implications of Paul’s declaration that Abraham and his offspring would receive the promise (singular) that he would be heir of the world, see especially (1) Douglas Moo, The Epistle to the Romans, in NICNT (Grand Rapids: Eerdmans, 1996), pp. 273-274; (2) John Murray, Epistle to the Romans, combined ed. (Grand Rapids: Eerdmans, 1968), pp. 141-142; and (3) Emil Brunner, The Letter to the Romans (Philadelphia: Westminster, 1959), pp. 36-40.
 The preposition in this statement conveys authority: ἀλλὰ συνέκλεισεν ἡ γραφὴ τὰ πάντα ὑπὸ ἁμαρτίαν.
 A.T. Robertson, Word Pictures in the New Testament (Nashville: Broadman, 1931), Gal 3:22. Johann Albrecht Bengel, Gnomon of the New Testament, ed. M. Ernest Bengel and J. C. F. Steudel, trans. James Bryce, vol. 4 (Edinburgh: T&T Clark, 1860), p. 29.
 “But, with the help of the Holy Spirit, the prisoners’ very consciousness of their galling bondage and of their total inability to burst their chains, causes them to yearn for a divine Deliverer and to shout for joy when they hear his approaching footsteps,” (William Hendriksen, Galatians and Ephesians, combined ed. (Grand Rapids: Baker, 1979), p. 144).
 Alvah Hovey, Commentary on the Epistle to the Galatians, in American Commentary (Philadelphia: American Baptist Publication Society, 1890), p. 48.