21 Tell me, you who desire to be under the law, do you not listen to the law? 22 For it is written that Abraham had two sons, one by a slave woman and one by a free woman. 23 But the son of the slave was born according to the flesh, while the son of the free woman was born through promise. 24 Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar. 25 Now Hagar is Mount Sinai in Arabia; she corresponds to the present Jerusalem, for she is in slavery with her children. 26 But the Jerusalem above is free, and she is our mother. (Galatians 4:21–26)

A Genesis Story Paul Uses As An Illustration (21-26)

At this point in Galatians, Paul decided to cap his scriptural defense of the gospel of grace with a story from Scripture.[^1] Paul was shocked that some in the Galatian church, after receiving Christ's gospel, contemplated living under the law (21). Clearly, they were not listening to the demanding nature of the law (21). And Paul could not understand why they wanted to rely on the it for their standing with God.

So Paul went all the way back to Genesis and retold the story of Hagar, Sarah, and the birth of each of their sons. Paul had already utilized Abraham's life in Galatians as foundational to the Christian faith, so it made sense he would draw from father Abraham's story one more time.

Paul used a well-known portion of Abraham's life so he could illustrate the truth that there are two ways to relate to Abraham. He had, after all, two main sons, Ishmael and Isaac (22). The portion Paul chose is one of the more disturbing parts of Abraham's biography, but Paul used the story as a way to show there are two ways to become a son of Abraham. The story itself shows God's grace comes by promise and faith, not personal righteousness and works, because it is not a passage that glorifies Abraham's life, decisions, or morality in any way. There are elements of it that are painful to read—still, God chose Abraham.

In the story, years after Abraham had believed God's promise that through him one would come who would bless the whole world, Abraham and Sarah remained childless. So Sarah concocted a plan that, to their credit, was culturally acceptable in their day—though it is abhorrent in ours, and God certainly did not condone it. Sarah told Abraham to impregnate a household servant named Hagar, which he did, and she had a son named Ishmael. But years later, God announced that Ishmael was not the line he would work through but that Sarah would have a son of her own. Even though Abraham and Sarah were very old—according to Romans, their bodies were as good as dead!—God fulfilled his promise, and miracle baby Isaac was born (Rom. 4:19).

Then, in a masterstroke, Paul played off the differences between these two sons of Abraham when he said he would interpret their story allegorically (24). Paul isn't introducing a new style of biblical interpretation—wild allegory!—but is admitting that he is going to use the Genesis story as a potent illustration of the struggle between law and grace.[^2] This is important to remember, especially since Hagar and Ishmael are used negatively as a way to describe legalists. In the Genesis account, Hagar and Ishmael are spoken of tenderly and with great honor—God saw them, valued them, and ultimately blessed them. But Paul's usage of their story here is a symbolic illustration of the ongoing battle between grace and works.[^3]

This argument was important because, by the first century, many in Judaism thought they were right with God by a mere ancestral claim to Abraham and through law-keeping. And this thought was creeping into the predominantly non-Jewish Galatian church: Maybe we need to become Jewish and adopt Jewish customs to lay claim to being children of Abraham and, therefore, children of God. And this thought can make it way into our minds as well: Maybe my morality or views or personal righteousness are what approve me before God.

Paul wasn't the first New Testament figure to deal with this problem. John the Baptist had warned the crowds by saying, "Do not presume to say to yourselves, ‘We have Abraham as our father,’ for I tell you, God is able from these stones to raise up children for Abraham" (Matt. 3:9). And Jesus, in a long interchange with the religious leaders, said that while they were biological offspring of Abraham, they were not acting like Abraham, but more like their "father the devil" because they would not acknowledge the truth about Jesus (John 8:39-47).

John, Jesus, and Paul were in agreement that a claim to Abraham does not come through mere biology, nor does it come through keeping a legal code delivered to Abraham's descendants over four centuries after his death. It comes by faith in God's gracious promise. Not works, but faith. Not law, but grace. Not effort, but promise.

As an illustration, Paul was careful to detail the differences between the births of these boys.

• 1. One's mother was a slave, while the other's was free (22).
• 2. One was born because of human planning (the flesh), while the other was born because of God's promise (23).
• 3. In his illustration, Hagar represented the covenant instituted on Mount Sinai, where the law was delivered, while Sarah was represented by Mount Calvary, where grace flowed down (25).
• 4. Hagar represented present day Jerusalem, a place Paul was very familiar with, a place filled with people who, by that time, were trying to earn their standing before God (25). Sarah, however, represented the Jerusalem above, which is spoken of in Scripture as the "city of the living God," the eternal and future home of all God's children (25, see Heb. 12:22, Rev. 21:2). By calling it "the Jerusalem above" and not "the future Jerusalem," Paul hints that though this city will be revealed in the future, it can be accessed right now by simple faith in Jesus.

The passage is not meant to leave you perplexed. Though the biblical world Paul referred to with Abraham's story confuses some, Paul's intention was to add light to the radical truth of the gospel with his illustration. To Paul—and the Spirit—this is a capstone consideration. By faith in Jesus, we become children of promise, born into freedom, and part of God's forever kingdom.

Every part of this illustration is meant to contrast law and grace, works and faith, legalists and true Spirit-filled Christians. If you are in Christ, (1) you belong to Sarah because you were born into freedom, (2) you are part of Calvary's New Covenant, (3) and you are a citizen of the heavenly Jerusalem that is and is coming.

But how does Paul apply his illustration? Let's spend the rest of our time together briefly considering four applications of the truth Paul laid out by contrasting Hagar and Sarah.

Applying Paul's Illustration (27-31)

1. Rejoice In Spiritual Barrenness (27).

27 For it is written, “Rejoice, O barren one who does not bear; break forth and cry aloud, you who are not in labor! For the children of the desolate one will be more than those of the one who has a husband.” (Galatians 4:27)

This is a quotation from Isaiah 54:1. In its original context, it was not about Hagar and Sarah but was spoken to Israel about their future. After a long period of disobedience, God was going to push them into exile, but their future was still bright. One day, from the barrenness of exile, they would explode in population. This was fulfilled—at least partly—in the Christian church, which flowed from the Jewish Messiah. Even though Israel was barren, empty, and helpless, God would do amazing things in them—the vast multitudes of the church would be born from the barrenness of first century Judaism.

What Paul is saying here is that we can rejoice in the barrenness of our depravity before God because it is not the end of the story. God prospers the spiritually poor who come to him in simple faith. As Jesus said, “Blessed are the poor in spirit, for theirs is the kingdom of heaven" (Matt. 5:3).

The legalists thought they had good works, morals, and rule-keeping that could help them stand approved by God. But the gospel enables us to rejoice that we come to God as spiritual paupers without anything in our hands to please God. Despite this, God becomes completely and totally satisfied and overjoyed with us by the blood of his Son. Though we came to him "dead in trespasses and sins," he makes us alive by his grace (Eph. 2:1). Though we were spiritually barren, God still loves and chooses us.

I hope you can bring this home and into your heart. When we slip into legalism, we are decimated by our failures because we are trusting them to approve us before God. Eventually, we simply give up and tap out. But when steeped in grace, we are shocked to find that we are loved and accepted by God without any work of our own. Though barren, he loves us, and now fruit can come from our lives.

If we were approved by God due to works, only the fertile, able, productive, and strong would be accepted. But we came to God like Sarah came into pregnancy—weak, without anything real to contribute, unproductive, as if we were dead—but God is able. And he looks for the barren, so we rejoice in our barrenness! He looks for the spiritually poor, blind, and destitute (Rev. 2:17). In the same way that the Old Testament's Sarah and Rebekah and Rachel and Hannah and Elizabeth all had children, even though they were unable, we were unable to produce righteousness on our own, but God has accepted us and made us fruitful. We can now take radical steps of obedience because we have been born into freedom, not slavery.

Think of Moses' life. He began humbly, but was quickly brought into the glory of Pharaoh's household. And as he aged and matured there, once he realized his Hebrew lineage, he began assuming God would use him to deliver his people. He thought his power and authority and position was the needed ingredient. Not to God. God allowed him forty more years of desert living as a fugitive. That's when God appeared to him at the burning bush, inviting him to be his instrument to set the people free. At that point, Moses felt weak and powerless. He could not believe God would use him. And that's what God needed—a spiritually barren man (Ex. 2-3).

This humility, this recognition of our low spiritual state, is what God can use. He looks for the spiritually barren, not the proud.

2. Expect A Struggle With Legalism (28-29).

28 Now you, brothers, like Isaac, are children of promise. 29 But just as at that time he who was born according to the flesh persecuted him who was born according to the Spirit, so also it is now. (Galatians 4:28–29)

Here, Paul geared the Galatian believer up for the inevitable battles they and all future gospel believers would have to endure. His way of preparing them was by reminding them of the episode when teenager Ishmael mocked and scoffed at toddler Isaac (see Gen. 21:9-10). In the same way that Ishmael persecuted Isaac, legalists will always persecute people who are clinging to God's grace alone by faith alone (29). In one sense, you could say that Paul's usage of the Genesis story is a perfect depiction of church history. Much of the strongest persecution the church has endured has come by the hands of legalists, those who feel something must be added to the gospel of grace. Grace alone by faith alone is insufficient to these persecutors.

And we must expect this struggle between law and grace. Ishmaels always persecute Isaacs. People who want to be approved by God because they think and do the right things will always chafe at those who are accepted by God through grace. Just as Cain was angered that God did not accept his sacrifice but did accept Abel's, legalistic people in the visible church will despise the freedom of those steeped in grace. Legalists hate grace. There will always be a legalistic contingent of the visible church that wars against the radical possibilities of grace. Ishmaels don't know what to do with Isaacs, just as Cains don't know what to do with Abels, whose sacrifice was accepted because he gave it by faith (Heb. 11:4).

Even within the recesses of our own hearts, doubts and arguments and old habits will surface, telling us that it is our performance that gains us God's affection. It is hard for us to feel completely free. We constantly battle a drift back into law—not as a practice, but as a way to be approved by God. Believers who love God obey God, so we will want to keep aspects of even the Old Testament law. But we struggle by often believing it is those works that approve us before God.

We are often like an older teenager or college student who is on the cusp of adulthood. They are beginning to feel their independence but are still under the authority of their parents. They can stay out late at night, but also know their parents will be checking their GPA. In a similar way, we feel free and loved and accepted by God through Jesus, but we then revert back to the parental authority the law had over us. But this has been Paul's point: when you receive Jesus, you receive full adult sonship before God. You have graduated with honors from the law's authority and are now free to respond and live before God! But you should expect a perpetual struggle with legalists, even the legalist within.

3. Purge Anti-Gospels (30).

30 But what does the Scripture say? “Cast out the slave woman and her son, for the son of the slave woman shall not inherit with the son of the free woman.” (Galatians 4:30)

In the Genesis passage, a point of contention arose when Sarah witnessed Hagar's son mocking toddler Isaac. She appealed to Abraham, and God told him to send Hagar and Ishmael out on their own. God would bless and care for them, but that isn't the point Paul is making here. He is using the story as an illustration of what the Galatian believers needed to do to the legalists in their midst—drive them away! Cut them off! Cast them out![^4]

Since law-keeping as a way to gain God's approval is in direct contradiction with Jesus' cross, believers must drive out that mentality. We "must recognize the incompatibility of man-made and God-made religion and respond by casting out the legalizers."[^5]

Paul's usage of the Genesis story here is nothing short of incendiary. Many Judaizers (legalists, Jewish nonbelievers) had likely used the story as an illustration of God's rejection of Gentiles, but Paul uses it in the opposite way. Those who are relying on Judaism—whether through biology or obedience—to save them must be driven out like Hagar!

Believers must drive out all the anti-gospels that creep into our minds and churches. When we think our own righteousness approves us before God, we must cast out the thought. When we think our own power can deliver us, we must cast out the thought. When we think our own wisdom can guide us, we must cast out the thought. When we think our own ingenuity can prosper us, we must cast out the thought.

And conversely, when we think our own shortcomings have disqualified us, we must cast out the thought. When we think God's strength is unavailable to us, we must cast out the thought. When we think God is looking for perfect people, we must cast out the thought. We must drive out these anti-gospels.

The life of Job is a good example of the need to cast out anti-gospels. Job suffered, and his friends all told him he must have sinned to bring such pain into his life. But everyone suffers, and God was doing something beautiful in Job and for all of us behind the scenes. But the perpetual voices aimed at Job told him that if he had simply performed better, he wouldn't be in such despair. It was an anti-gospel, and it had to be cast out. And you often find this anti-gospel alive and well when Christians suffer—What did I do wrong? What must I do to get out of this? Why am I being punished?

The tower of Babel is another example of an anti-gospel gone wild. As people gathered there, they believed they could build a structure reaching the heavens. They believed they could create a glorious society without God, making a name for themselves (Gen. 11:4). Through their own works, without God's grace, power, or strength, they thought they would thrive. Instead of humbly asking God for help and grace, they believed in the anti-gospel of works.

But as we preach the good news of the gospel of grace to ourselves every day, we become built up against anti-gospels when they well up within us. We grow to detect them more easily, and soon they begin to stand out in strange opposition to the true gospel.

Recently, I was working out in my garage when my daughters came home from winter camp. I didn't realize a friend was with them, and I also didn't think twice about what I was wearing. Workout shorts over a nice pair of tights, a snug little t-shirt, and a dew rag-styled sweatband. She is part of our church, and she couldn't stop laughing. To her, something was off with Pastor Nate. I pray we can come to the same place when anti-gospels appear. I pray we would grow to detect them, laugh at them, and then, as Paul said, quickly cast them out.

4. Know Who You Are (31).

31 So, brothers, we are not children of the slave but of the free woman. (Galatians 4:31)

Paul meant that Jesus' people are, in his illustration, descendants of Sarah, children of promise, connected to the New Covenant of Mount Calvary, and of the Spirit. This is who we are, and we cannot forget it because our remembrance of it is quite literally a life-or-death issue. When we recall that we are illustrations of God's majestic grace, we live well as gospel lights to the world around us. We embrace our position as a chosen race, royal priesthood, holy nation, a people for God's own possession—we proclaim the excellencies of him who called us (1 Pet. 2:9).

"As believers, a key component of the significance of our lives is that we are living, breathing symbols of the transforming grace of God that has freed us from our slavery to sin, death, the devil, and all the powers of this present evil age." —Matthew Harmon[^6]

But when we forget who we are, we begin to project to our world that we are self-made before God through our own personal morality or goodness. Our lives become pulpits proclaiming legalist mantras just like all the other religions of the world. But grace is different. And we are children of the free woman. We are children of grace, and we must not forget it.

Recently, I was out on a walk when I saw a hat lying on the side of the road. I suspected I had dropped mine the day before, and there it was. But when I inspected it, I realized it wasn't mine after all, so I kept on walking. As I did, I scratched my head and realized I was wearing the very hat I thought I had lost. It was right there, on my head. This is how it so often is regarding our identity in Christ. We slip into an attempt to prove ourselves to God, but the gospel reminds us we are already approved. We are already clothed with the righteousness of Jesus!

Conclusion

By God's grace, we have been brought from barrenness to fruitfulness, slavery to freedom, and law to grace. We now have an eternal and heavenly citizenship. One day, our city will arrive.

And it has all happened through the work of Christ. Just as Abraham's plotting and planning could not fulfill God's purposes, our efforts and attempts cannot gain our good standing before God. We needed his plan and power. And just as Sarah received a miracle child in Isaac, so we are born to God through the miracle of Christ's resurrection and the new birth of the Spirit. So when the anti-gospels roll in, let us stand firm against them!

[^1]: Barker, Kenneth L., and John R. Kohlenberger III. 2019. The Expositor’s Bible Commentary the Expositor’s Bible Commentary: Old & New Testaments. USA: Zondervan Academic. [^2]: Rydelnik, Michael, and Michael Vanlaningham, eds. 2014. The Moody Bible Commentary. Chicago, IL: Moody Press. [^3]: Keller, Timothy. 2013. Galatians For You. New Malden, England: Good Book Company. [^4]: Walvoord. 2003. The Bible Knowledge Commentary: New Testament. Colorado Springs, CO: David C Cook Publishing Company. [^5]: Barker, Kenneth L., and John R. Kohlenberger III. 2019. The Expositor’s Bible Commentary the Expositor’s Bible Commentary: Old & New Testaments. USA: Zondervan Academic. [^6]: Harmon, Matthew S. 2021. Galatians: Evangelical Biblical Theology Commentary. Lexham Academic.