Two Mothers, Two Covenants, Two Jerusalems Text: Galatians 4:21-31
Introduction: The Judaizing Temptation
The book of Galatians is Paul's theological war-axe, and he wields it with devastating precision against a particular kind of error that is perennial. It is an error that is always crouching at the door of the church. This is the error of the Judaizers, the men who wanted to add a little bit of law to the gospel of grace. They were not outright pagans; they were far more dangerous than that. They were the religious insiders, the men of reputation, who came along after Paul and told the Galatian Christians that faith in Jesus was a fine start, but in order to be truly complete, truly mature, they needed to add the works of the law, beginning with circumcision.
This sounds pious, does it not? It sounds like taking God seriously. "We believe in Jesus," they would say, "and we also believe in obeying God's law." But Paul identifies this mixture not as spiritual maturity, but as a different gospel entirely, which is no gospel at all. To add anything to the finished work of Christ is to subtract Christ. To add a drop of works-righteousness to the pure grace of God is to curdle the whole batch. It is to trade the freedom of a son for the slavery of a hired hand. It is to abandon the Father's house for the servants' quarters.
The Galatians were being tempted to go back. They were being tempted to put themselves under the law, to find their assurance and identity in their own performance. And so Paul, having argued from his own apostolic authority and from the doctrine of justification by faith, now turns to the Old Testament Scriptures themselves. He is about to show these Judaizers that the very law they want to run back to, the books of Moses, testifies against them. He is going to show them that from the very beginning, in the household of Abraham, God established two ways of relating to Him. One is the way of the flesh, of human effort, of slavery. The other is the way of the Spirit, of divine promise, of freedom. There are two mothers, Hagar and Sarah, and you must choose who your mother is. You cannot have both.
This is not some abstract theological dispute. This is intensely practical. It determines whether you live your Christian life with the joyful confidence of a beloved son, or with the anxious dread of a slave who is never sure he has done enough. It determines whether you see God as a gracious Father or as a demanding taskmaster. It determines whether your spiritual life is characterized by freedom or by bondage.
The Text
Tell me, you who want to be under law, do you not listen to the Law? For it is written that Abraham had two sons, one by the servant-woman and one by the free woman. But the son by the servant-woman had been born according to the flesh, while the son by the free woman through the promise. This is spoken with allegory, for these women are two covenants: one from Mount Sinai bearing children into slavery; she is Hagar. Now this Hagar is Mount Sinai in Arabia and corresponds to the present Jerusalem, for she is in slavery with her children. But the Jerusalem above is free; she is our mother. For it is written,
“REJOICE, BARREN WOMAN WHO DOES NOT GIVE BIRTH;
BREAK FORTH AND SHOUT, YOU WHO ARE NOT IN LABOR;
FOR MORE NUMEROUS ARE THE CHILDREN OF THE DESOLATE ONE
THAN OF THE ONE WHO HAS A HUSBAND.”
And you brothers, in accordance with Isaac, are children of promise. But as at that time he who was born according to the flesh was persecuting him who was born according to the Spirit, so it is now also. But what does the Scripture say?
“CAST OUT THE SERVANT-WOMAN AND HER SON,
FOR THE SON OF THE SERVANT-WOMAN SHALL NOT BE AN HEIR WITH THE SON OF THE FREE WOMAN.”
So then, brothers, we are not children of a servant-woman, but of the free woman.
(Galatians 4:21-31 LSB)
An Appeal to the Law Itself (vv. 21-23)
Paul begins with a sharp, almost sarcastic question.
"Tell me, you who want to be under law, do you not listen to the Law?" (Galatians 4:21)
The Judaizers were all about the Law of Moses, the Torah. Paul says, "Fine. You want to live by the book? Let's open the book." He is not rejecting the Old Testament; he is about to show them they do not understand it. They are using the Law in a way the Law itself forbids. They are reading it with a veil over their hearts, just as Paul says of the unbelieving Jews in 2 Corinthians. They hear the words, but they miss the music.
He then takes them to the story of Abraham's two sons. This is a masterstroke. The Judaizers revered Abraham. To be a son of Abraham was everything. Paul agrees, but forces the question: which son are you?
"For it is written that Abraham had two sons, one by the servant-woman and one by the free woman. But the son by the servant-woman had been born according to the flesh, while the son by the free woman through the promise." (Galatians 4:22-23)
Here is the fundamental contrast. Ishmael, the son of Hagar the slave, was born "according to the flesh." This was the product of human striving. Remember the story. God had promised Abraham a son, but Abraham and Sarah grew impatient. They decided to "help God out." Sarah gave her servant Hagar to Abraham, and Ishmael was conceived. It was a reasonable plan. It was a pragmatic solution. It was a work of the flesh. It was Abraham trying to secure the promise by his own strength and ingenuity.
Isaac, on the other hand, was born "through the promise." His birth was a flat-out miracle. Abraham was as good as dead, and Sarah's womb was dead. From a human standpoint, it was impossible. But God had promised, and God brought it to pass by His own supernatural power. Isaac's very existence was a testimony to the grace of God, not the achievement of man.
An Allegory of Two Covenants (vv. 24-27)
Paul now explains the deeper meaning of this historical account.
"This is spoken with allegory, for these women are two covenants: one from Mount Sinai bearing children into slavery; she is Hagar." (Galatians 4:24)
When Paul says this is an allegory, he is not saying the historical events didn't happen. He is saying that these historical events were providentially designed by God to teach a deeper theological truth. This is typology. God writes the story of redemption, and He often uses the earlier chapters to foreshadow the later ones. Hagar and Sarah are not just two women; they represent two covenants, two ways of relating to God.
Hagar, the slave woman, represents the covenant from Mount Sinai. This is the Mosaic covenant, the Law. And what does this covenant produce when it is approached as a means of salvation? It produces slaves. If you try to approach God on the basis of your law-keeping, you will not become a son; you will become a slave, born into bondage. Why? Because the law demands perfection, and you cannot provide it. The law, when used as a ladder to heaven, only shows you how high heaven is and how short your ladder is. It leaves you in a state of constant fear and insecurity, like a slave who is always afraid of the master's whip.
Paul then connects this Hagar/Sinai covenant to the Jerusalem of his own day.
"Now this Hagar is Mount Sinai in Arabia and corresponds to the present Jerusalem, for she is in slavery with her children." (Galatians 4:25)
This would have been a shocking, offensive statement to his opponents. The earthly Jerusalem, the city of the great Temple, the center of Jewish worship, Paul says, is in the line of Hagar the slave. The first-century Jewish establishment, which had rejected its Messiah, was operating "according to the flesh." They had turned the covenant of God into a system of national and ethnic pride, a works-righteousness project. They were in bondage to their traditions and their unbelief, and they were producing children of that same bondage.
But there is another Jerusalem.
"But the Jerusalem above is free; she is our mother." (Galatians 4:26)
This is the heavenly Jerusalem, the city of the living God. This is the true Church, the communion of all saints in heaven and on earth. And she is our mother. We are not born from the earth up, through our own striving. We are born from heaven down, by the Spirit of God. This mother is free, and she only gives birth to free children. Our identity is not in a physical place or a physical lineage, but in this spiritual city, the bride of Christ. When we gather for worship, we are not coming to an earthly mountain; we are coming to the heavenly Mount Zion (Heb. 12:22). This is our home country.
Paul then quotes from Isaiah 54 to show that this has always been God's plan. He has always intended to build His family through the barren woman, through the one who could not produce children on her own. Sarah was barren. Hannah was barren. And the Gentile church was barren, without God and without hope in the world. But God, by His grace, promised that the desolate one would have more children than the one who had a husband. Grace always out-produces the flesh.
Heirs and Persecutors (vv. 28-31)
Paul now brings the application directly to the Galatian believers.
"And you brothers, in accordance with Isaac, are children of promise... But as at that time he who was born according to the flesh was persecuting him who was born according to the Spirit, so it is now also." (Galatians 4:28-29)
He tells them plainly: You are Isaacs. Your standing with God is not based on your performance, but on God's promise. You were born supernaturally, by the work of the Spirit. This is your identity. But this identity comes with a consequence. Just as Ishmael mocked and persecuted the young Isaac (Genesis 21:9), so the children of the flesh will always persecute the children of the Spirit. Legalism is never content to live and let live. The religion of human achievement is always threatened by the religion of grace. Why? Because grace exposes all our self-righteous projects as filthy rags. The slave always hates the true son because the son's existence is a constant reminder that he is free, and the slave is not.
This is why the Judaizers were troubling the Galatian churches. It was the ancient enmity between the two seeds, the two lines, playing out once again. The children of Hagar were persecuting the children of Sarah.
So what is the solution? What does God's word command?
"But what does the Scripture say? 'CAST OUT THE SERVANT-WOMAN AND HER SON, FOR THE SON OF THE SERVANT-WOMAN SHALL NOT BE AN HEIR WITH THE SON OF THE FREE WOMAN.'" (Galatians 4:30)
The answer is not compromise. It is not dialogue. It is not finding a middle ground. The answer is expulsion. "Cast out the slave woman." There can be no mixing of these two principles. The gospel of grace and the religion of works cannot co-exist in the house of God. The son of the slave woman will not be an heir with the son of the free woman. You cannot be an heir by grace and an heir by works simultaneously. You must choose. To try and have both is to have neither.
Paul concludes with a ringing declaration of freedom.
"So then, brothers, we are not children of a servant-woman, but of the free woman." (Galatians 4:31)
This is the heart of the matter. Christian, know who you are. Your mother is the heavenly Jerusalem. You were born of a divine promise. You are an heir, not because of what you have done for God, but because of what Christ has done for you. You are not a slave, nervously trying to earn your keep. You are a son, living in the freedom of the Father's love.
Conclusion: Live as Sons, Not Slaves
The choice that faced the Galatians faces us today. The temptation to add our own works to the gospel is subtle and constant. It can take many forms. It can be the temptation to base our assurance on the quality of our quiet times, or our success in parenting, or our theological precision, or our moral performance. It is the temptation to look anywhere but the cross of Christ for our standing before God.
Whenever we do this, we are siding with Hagar. We are putting the chains of slavery back on. We are acting like orphans, trying to earn a place in the family that is already ours by right of adoption.
But Paul's message is clear. You are children of Sarah, the free woman. You are children of the promise. Your life began with a miracle of grace, and it must be lived in the same way. This means your identity is secure. It means your inheritance is guaranteed. It means you are free. Free from the condemnation of the law. Free from the fear of God's wrath. Free from the need to prove yourself.
Therefore, live like it. Live as free sons and daughters. Obey God, not out of slavish fear, but out of grateful love. Fight sin, not to make yourself acceptable to God, but because you already are acceptable in Christ. And when the voice of the slave-driver whispers in your ear, telling you that you have not done enough, you must respond with the word of God. You must tell that voice that you have a new mother, the Jerusalem above. And you must cast out the slave woman and her son, for you are not a child of bondage, but a child of the free woman.