RPM, Volume 20, Number 8, February 18 to February 24, 2018

You Are Children of Promise

Galatians 4:21-31

By Kim Riddlebarger

Before his conversion to Christianity, Paul had been a student of the famed Rabbi Gamaliel, and as an up and coming Rabbi himself, Paul was well-known for his zeal for the religion of Israel and his persecution of the church. Now the apostle to the Gentiles, Paul responds to the false teachers plaguing the Galatians, who suddenly find themselves dealing with someone who was a master of demonstrating how Jesus Christ was the sum and substance of the Old Testament messianic expectations of Israel. Once again, Paul will open the Scriptures and use them to refute one of the Judaizer's main arguments.

Paul has expressed his anger, his amazement and his sorrow over what was happening to the Galatian Christians. When he had been in the Galatian region previously, recuperating from what appears to be a serious illness which had affected his vision, Paul had used the opportunity to preach the gospel to the Galatians, as he puts it, to publicly placard Christ to them. God, in his providence and grace, used Paul's preaching as the means to call many people living in the region to faith in Christ (Jew and Gentile), and as a result, a number of churches were established. The Galatians had responded favorably to the gospel and they warmly embraced Paul as a kind of spiritual father. He had led them to a knowledge of the Savior, and so they demonstrated great hospitality to him, nursing him back to health when he fell ill. Having left the area to continue on in his missionary activity, reports soon got back to Paul that something was now amiss. Wolves had entered into these churches and were deceptively leading the Galatians astray in great numbers.

These wolves, now known to us as the Judaizers, were Jewish converts to Christianity. They had come to believe that Jesus was Israel's Messiah, but, apparently, they did not believe that Jesus' obedient life and sacrificial death were sufficient to save sinners from God's wrath. Hence, the Judaizers were teaching that Gentile coverts to Christianity must submit to ritual circumcision, keep the Jewish religious calendar and dietary laws and obey the law of Moses as a means of obtaining or maintaining justification, or a "right standing" before God.

According to Paul, the Judaizers were teaching a different gospel which was no gospel at all, and in doing so, placed themselves under God's curse. Paul is angry with these false teachers, whom he believes have deceptively entered these churches and were spying on those exercising their liberty in Christ. But when he addresses the Galatians—people he has led to faith in Christ and who have demonstrated great hospitality to him—Paul is utterly bewildered. How could these people who he has lead to Christ now turn from Christ and follow these deceivers who want to lead the Galatians back into slavery? Jesus Christ had died to set the Galatians free. But the Judaizers were doing their best to convince these people that slavery to the law and "the basic principles of the world," was somehow better than freedom in Christ.

Having concluded a series of personal remarks and making an impassioned appeal to the Galatians not to fall for the schemes of these deceivers, Paul again returns to an argument from redemptive history and the Old Testament Scriptures which illustrates the way in which the Judaizers misrepresent God's saving purposes. Paul begins to set out this point in verses 21-31.

21 Tell me, you who want to be under the law, are you not aware of what the law says? 22 For it is written that Abraham had two sons, one by the slave woman and the other by the free woman. 23 His son by the slave woman was born in the ordinary way; but his son by the free woman was born as the result of a promise. 24 These things may be taken figuratively, for the women represent two covenants. One covenant is from Mount Sinai and bears children who are to be slaves: This is Hagar. 25 Now Hagar stands for Mount Sinai in Arabia and corresponds to the present city of Jerusalem, because she is in slavery with her children. 26 But the Jerusalem that is above is free, and she is our mother. 27 For it is written: "Be glad, O barren woman, who bears no children; break forth and cry aloud, you who have no labor pains; because more are the children of the desolate woman than of her who has a husband." 28 Now you, brothers, like Isaac, are children of promise. 29 At that time the son born in the ordinary way persecuted the son born by the power of the Spirit. It is the same now. 30 But what does the Scripture say? "Get rid of the slave woman and her son, for the slave woman's son will never share in the inheritance with the free woman's son." 31 Therefore, brothers, we are not children of the slave woman, but of the free woman.

After making his personal appeal earlier in chapter 4 (vv. 8-20), Paul now changes focus and returns to a discussion of the way in which the Judaizers were misusing the Old Testament. This section of Galatians gives us additional evidence of one of Paul's favorite rhetorical devices (the refutation of the arguments of the Judaizers by taking their own proof-texts and using them against them) and in doing so, clearly demonstrating that the biblical evidence is on Paul's side. We have seen Paul do this throughout this epistle, and it would be helpful to briefly survey them now.

In Galatians 3:6, Paul quoted from Genesis 15:6, in order to demonstrate that Abraham, the great patriarch of Israel, was justified by faith alone and not by works. This point by itself is utterly fatal to the Judaizers' arguments. But Paul is not going to let up. He employs same rhetorical technique in Galatians 3:10, when he quotes from Deuteronomy 27:26—"cursed is everyone who does not continue to do everything written in the Book of the Law." Paul's point, here, is basically, "if you want to be justified by means of obedience to the Law, consider what the Law says!" If you guys want law, I'll give you law! For when we actually stop and consider what the law requires of us, we immediately discover that God demands perfect obedience from us to the law of Moses in thought, word and action, if we are to be justified on the basis of our works. For those of you listening to Judaizers, don't forget to consider this— "If you do not maintain perfect obedience you come under God's curse!"

As we saw in Galatians 3:16, Paul again makes his point that the Judaizers were misreading the Old Testament, this time by appealing to the promise that God made to Abraham, and to his seed, who is none other than Jesus Christ. The promises of a coming Messiah and the gift of the Holy Spirit come to both Jew and Gentile alike, through the means of faith, not through works. Thus, by demonstrating that the Old Testament points us forward to Jesus Christ, Paul is able to prove that his gospel is not an innovation! His gospel is the same gospel that Abraham believed and is the same doctrine taught throughout the Old Testament. Jesus Christ is the fulfillment of all of these Old Testament prophecies, and even though the Judaizers may claim to have embraced Christ as the Messiah, their argument that salvation is based upon Christ plus human merit, clearly demonstrates that while the Judaizers may have been right about the person of Christ, they certainly did not understand the work of Christ.

Paul continues this same approach in Galatians 4:21 and following. Paul takes one of the main arguments of the Judaizers—which was based upon a misrepresentation of the Biblical accounts of Sarah and Hagar, the two mothers of Abraham's children, Isaac and Ishmael—and uses it to show how the Judaizers had misunderstood or misrepresented the whole point of the account. In fact, based upon the nature of Paul's argument here, it is indeed possible to reconstruct some of what the Judaizers were falsely teaching the Galatians in this regard. Their argument runs something like this: The Jews are the true people of God and had their beginning with Abraham and God's promise to him and his descendants. But God's covenant with Abraham—and, therefore, with the nation of Israel—had been radically redefined by the Sinaitic Covenant that God made with Moses at Mt. Sinai. In other words, the covenant of grace was redefined by the Covenant at Sinai as a covenant of works.

Indeed, the practical application of the Judaizer's basing the fulfillment of promise upon obedience to the law of Moses, is that while "God's promise was given to Abraham and his offspring … the obligations of the offspring were clearly revealed in the law; hence, to receive the spiritual blessing, it was necessary to fulfill the demands of the law." 1 In other words, the promise does not come to God's people through faith alone. Rather, according to the Judaizers, God's people receive the promise through obedience to the Ten Commandments. Given the fact that Paul specifically mentions the two women here, Hagar and Sarah, it is very likely that the Judaizers were indeed appealing to "the story of Abraham and the two women: the Sarah-Isaac-Moses-Law-Jerusalem line alone represented the true offspring of Abraham, and if the Gentiles were to have a part in it, they had to be incorporated through circumcision into Abraham's family and acknowledge to sovereignty of Jerusalem." 2

If the Judaizers were correct about this, this means that the reception of the promise is contingent upon the human obedience to law and means that what was central under the old covenant—circumcision, obedience to the law of Moses, keeping dietary laws, following the Jewish calendar, revering the temple, and placing the earthly Jerusalem at the center of the religious life of God's people—remains central even after the coming of Christ. This amounts to a complete reversal of redemptive history, a return to the bondage of slavery, and a denial that the redemptive work of Christ is sufficient to save. It is another gospel.

Paul is a follower of Jesus Christ. He now reads the Old Testament through the eyes of faith in the Son of God and re-interprets the account of Abraham, Sarah and Hagar in light of the coming of Christ. This means that Paul now sees the entire Old Testament, including the Genesis accounts mentioned here, through the lens of Jesus Christ. "Against this reasoning [of the Judaizers]" notes one writer,

Paul brings out the spiritual meaning of the text apart from its literal historical sense; he gives the name Hagar a fresh interpretation, pointing out that she represents the law and slavery. (This is why Hagar is specifically mentioned in v. 24. Paul has to make it unmistakably clear which of the two women represents the Sinaitic covenant). Here the physical descendants of Sarah become the spiritual descendants of Hagar, while the physical descendants of Hagar, interpreted of Gentiles in general, become the spiritual descendants of Sarah. Paul then quotes Isa. 54:1 (in 4:27) to show that the future belongs with the Christian church and not with Judaism, finally confirming this by returning to the record in Genesis (Gen. 21:9 ff.). 3

This re-interpretation of the role of Abraham and his descendants completely turns the tables on those who saw themselves as defenders of the religion of Israel. Paul has just placed them in the same category as the descendants of Ishmael! The Judaizers knew exactly what Paul meant by this! They were not heirs to the promise! They are apostates from the faith.

At this point, it would helpful to turn to the specific points of Paul's overall argument. To begin with, Paul recalls the facts of the Genesis account in verses 22-23. Abraham had two sons, Ishmael, and his younger brother by 14 years, Isaac. Each had a different mother. According to Genesis 16:1-16, Hagar was a slave and the mother of Ishmael. According to Genesis 21:2-5, Sarah gave birth to Isaac and was a free woman. The son born by the slave woman was born "in the ordinary way," literally by means of natural procreation. But the son born to Sarah was born according to the promise, meaning not in the ordinary way.

As Genesis 17:17 makes clear, natural procreation and the fullfilment of the promise seemed impossible since Abraham was at least one hundred and Sarah at least ninety. The birth of Isaac, while the product of natural procreation, nevertheless, came about by supernatural means, namely the restoration of Sarah and Abraham's ability to bear children.

In contrast to the Judaizers, Paul interprets the historical events allegorically in light of the coming of Christ and the attempted reversal of redemptive history by the Judaizers. This does not mean that Paul understands the Genesis account to be fictional or non-historical. It does mean that Paul uses the historical events to make an important theological point which was certainly not evident to Moses at the time Genesis was written. It is this ability to find Christ in the Old Testament that is in view, at least in part, when we speak of Spirit-given prophecy in the apostolic church—that is, the Holy Spirit enabling us to see the reality of Jesus Christ as the fulfillment of Old Testament type and shadow. It is important to note that in this sense, the New Testament interprets the Old Testament.

Using one of the texts to which the Judaizers were most likely appealing as a proof-text for their argument that obedience to law fulfills the Abrahamic promise, Paul asserts that both women, Hagar and Sarah, are each illustrative of two respective covenants. On the one hand, Hagar stands for the law and the covenant given on Mt. Sinai, a covenant in which the people of God swore the oath of ratification and promised obedience to the demands of the law. Hagar's children were, therefore, born in bondage, because they are born "under law." The children produced by the union of a master and one of his slaves are not destined to be free, but are instead, born as slaves. In this case, these are the natural children, children born in the "ordinary way." Such was the case of the spiritual children of Hagar who—according to Paul's re-interpretation of this—are the Jews, born in slavery to the law, since the law was given, in part, to excite and exacerbate human sinfulness, not to provide a means of justification (cf. Romans 7:7-8; 21).

Sarah, on the other hand, is the free woman who is the spiritual mother of those who are united to Christ through faith. Sarah represents the covenant of grace—a covenant in which God himself swears an unconditional oath to be God to his people and which includes children of promise, children not born in the natural way. Hagar's children, however, are the natural children—those enslaved to law—who are the citizens of the earthly Jerusalem (v. 25). Just as Hagar was in physical bondage as a slave, so the spiritual children of Hagar—the Jews—are themselves enslaved to the law, and that which Paul has already called the stoichiea, or the "elementary principles of the world" (4:9). It is this bondage to the law and the basic principles that enslaves both the historical children of Hagar, the physical descendants of Ishmael, as well as the spiritual children of Hagar, the Jews, the citizens of the earthly Jerusalem. Thus, Paul's exegesis of this text flips the Judaizer's argument on its head.

For Paul, the key in all of this is the city he speaks of as the "Jerusalem above," (v. 26), a city whose inhabitants are not in bondage, but free. There is some very interesting word play here in the original language, and this is yet another instance of Paul explaining things eschatologically. That is, Paul sees salvation in terms of "this age" and an "age to come." The "age to come" is an age of redemption ushered in by the coming of Jesus Christ, and stands in marked contrast to "this evil age" which is passing away. One commentator explains this very difficult point as follows:

In opposing to "the Jerusalem of today" (v. 25) "the Jerusalem above" and not, as might be expected, "the Jerusalem to come," it might seem that Paul has confused two distinct though related forms of the concept of a New Jerusalem familiar from the OT: that which views it as coming in the eschatological future, over against the present Jerusalem (cf. Zech. 8:1-8), and that which sees it as already existing in heaven, over against the earthly Jerusalem (e.g., Isa. 62; cf. Heb 12:22; Rev. 3:12; 21:2, 9 ff.). What [Paul] has actually done, however, is to mingle the two forms, the temporal and the spatial, in such a way as to indicate that the Jerusalem to come has already arrived (note the twice repeated "is") in the form of the heavenly, spiritual Jerusalem. He can do this … easily because Heb. olam has both a spatial sense ("world") and a temporal sense ("age") and the apocalyptic contrast of This Age and the Age to Come implies also the contrast of this world and the "other" world. This Jerusalem, says Paul, is our mother—that is, the mother of those who are Christians. 4

Paul's point is that we are to understand "the Jerusalem that is above," as the city which represents "the age to come," and our redemption in Christ. According to Revelation 21:2, this heavenly Jerusalem is even now coming down out of heaven. This city is that spiritual Mt. Zion, to which the author of Hebrews refers in Hebrews 12:22—the heavenly Jerusalem, the city of the living God—to which we as Christians now freely approach as citizens of heaven. The heavenly Jerusalem is also the eschatological home of those in the covenant of grace. The Jerusalem from above stands in marked contrast to the earthly Jerusalem, the city of the law, and in which citizenship is based upon the principle of human obedience and the covenant of works, things characteristic of the present day city of Jerusalem with its temple and Torah.

Though this is difficult to grasp, Paul is clearly an eschatological thinker, who sees history as the overlap of two great ages of redemption, "this age," and the "age to come." This means that as Christians, we are citizens of the heavenly city which is above, though we still live in "this age" (the earthly city) anticipating "the age to come" in all of its fullness and glory. This dual citizenship ends with the return of Christ when "this age" finally and completely passes away and the "age to come" is a present, visible and final reality. This is why Paul speaks of us as children of promise—we live in the present in light of Christ's life and death, anticipating the citizenship and the inheritance yet to come. This is what we mean when we speak of "the already" and "the not yet."

As a further proof of his point in 4:27, Paul picks up additional themes from the Genesis account. Sarah was barren with no children (Genesis 11:30). But we are told in Genesis that she shouted with joy at the birth of Isaac (Genesis 21:6 ff). Indeed, her children through Isaac were more numerous than those of Hagar through Ishmael. Thus the church, as the spiritual descendants of Sarah and children of the promise were more numerous than those of Hagar, since Hagar's children were enslaved to law and were separate from the people of God. And since Sarah's children included both believing Jews and Gentiles, Paul sees this as a fulfillment of the promise made to Abraham and Isaac, namely that their descendants would become a great nation and be more numerous than the stars in the heavens. 5

In verse 28, Paul now applies the allegory he has just set forth to the contemporary situation in the Galatian church. Those who are trusting in the merits of Jesus Christ through faith alone, and not in the elementary principles of works-righteousness, are the true children of Isaac and the children of promise. Therefore, the children of promise are children born by supernatural means, not in "the ordinary way" and are heirs to all the inheritance. The Galatian Christians owe their very existence to the unconditional promise that God made under the terms of the covenant of grace, and not to their own obedience to the law of Moses. This is most clearly seen in the promise that God would justify the Gentiles, as he did Abraham, by grace alone, through faith alone, on account of Christ alone.

In verses 29-30, Paul adds two final arguments from the Genesis account. First, at that time, the natural-born son, Ishmael, (literally "born according to the flesh") reported in the account in Genesis 21:9, actually mocked the son that was born according to the promise (literally "according to the Spirit" in Paul's words). And so Paul can conclude in verse 30 about the situation on Galatia, "it is the same now." In abandoning the doctrine of justification by grace alone, through faith alone, on account of Christ alone, the Judaizers, in effect, mock the gospel and those who have trusted in it. It is the Judaizers who seek to reverse redemptive history. It is the Judaizers who seek to divide what Christ has joined together into one body—Jew and Gentile. It is the Judaizers who seek for themselves what belongs to the true heirs to the inheritance. It is the Judaizers who seek to return to slavery. It is the Judaizers who are the natural children, children of Hagar. It is the Judaizers, who believing and teaching these things, mock God!

As to the second point, Paul reminds us in verse 30 that according to the Genesis account—Genesis 21:10-12—the slave woman and her son are to be cast out! The religion of promise, the religion of the covenant of grace, the religion of justification by faith alone, cannot co-exist with the religion of law, the religion of the covenant of works, the religion of justification by faith and works. This is why those who preach, teach or believe another gospel are therefore, anathema (Galatians 1:6-10). Since the Judaizers are the children of Hagar, and like Ishmael mock the true heir, they too, must be expelled!

As we conclude, it would be helpful to set out some of the contrasts that Paul has set forth in his various arguments against the Judaizers:

Righteousness through law-keeping is contrasted with righteousness through faith alone

- Slavery to the law and the "basic principles" is contrasted with freedom in Christ

- The covenant of works is contrasted with the covenant of grace

- Mt. Sinai is contrasted with Mt. Zion (actually Mt. Calvary)

- The law is contrasted with the gospel

- Hagar (the slave woman) is contrasted with Sarah (the free woman)

- Ishmael (born according to the flesh) is contrasted with Isaac (born according to the promise-Spirit)

- The citizens of the earthly Jerusalem (legalisms-Judaizers) are contrasted with citizens of the Jerusalem above (Christians)

It is with these things in mind that Paul now reminds the Galatians in verse 31 of what has become so very clear: "Therefore brothers, we are not children of the slave woman, but children of the free woman." Paul's point is now plain—why would free people, children of the free woman, want to once again take up the shackles of slavery, renounce their inheritance and embrace Hagar, the spiritual mother of slavery to the law and the basic principles of this world? Why would a free people reject their citizenship in the "Jerusalem above," preferring instead to reside in the earthly Jerusalem, in which the light of the gospel has been extinguished by the darkness of the law, the temple and type and shadow? The Judaizers have turned back the course of biblical history, and in doing so, have turned their backs upon the one called the "light of the world"—Jesus Christ—Israel's prophet, priest and king.

As believers in Jesus Christ, we are Sarah's children. We are the children of promise, children not born in the "ordinary way." For we have been called to faith in Christ through the word, and born in a supernatural way—through the sovereign electing grace of God—not by means of natural generation and the racial identity of our mother. In Christ we are justified, given the gift of the Holy Spirit, become heirs to the promise, adopted into God's family, clothed with Christ through baptism, and can cry out "Abba, father." We are children of the promise. We are free. We are citizens of the Jerusalem above. Does anybody want to go back to Egypt? This is what the Judaizers would have us to do.

No, as children of the promise and heirs to the inheritance, let us do as the author of Hebrews (12:22 ff.) exhorts us to do—draw near,

to Mount Zion, to the heavenly Jerusalem, the city of the living God. [For] you have come to thousands upon thousands of angels in joyful assembly, to the church of the firstborn, whose names are written in heaven. You have come to God, the judge of all men, to the spirits of righteous men made perfect, to Jesus the mediator of a new covenant.



  1. Fung, Galatians, p. 220.
  2. Fung, Galatians, p. 220.
  3. Fung, Galatians, p. 220.
  4. Fung, Galatians, p. 210.
  5. Fung, Galatians, p. 211.
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