What Does Galatians 4:21-31 Mean?
Galatians 4:21-31 explains how the story of Abraham’s two sons illustrates two different ways of relating to God - one through human effort and one through God’s promise. Paul uses this Old Testament account (Genesis 16, 21) to show that trying to earn God’s favor by following religious rules leads to slavery, but receiving God’s promise by faith brings freedom. Isaac, the child of promise, was born by God’s power. We too become God’s children by grace, not by law.
Galatians 4:21-31
Tell me, you who desire to be under the law, do you not listen to the law? For it is written that Abraham had two sons, one by a slave woman and one by a free woman. But the son of the slave was born according to the flesh, while the son of the free woman was born through promise. Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar. Now Hagar is Mount Sinai in Arabia; she corresponds to the present Jerusalem, for she is in slavery with her children. But the Jerusalem above is free, and she is our mother. 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.” Now you, brothers, like Isaac, are children of promise. 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. 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.” So, brothers, we are not children of the slave but of the free woman.
Key Facts
Book
Author
Paul
Genre
Epistle
Date
circa 48-50 AD
Key Themes
Key Takeaways
- We are God's children by promise, not by law.
- Faith in Christ brings freedom; rule-keeping leads to slavery.
- True inheritance belongs to those born of the Spirit.
Context of Galatians 4:21-31
The story of Abraham's two sons is a powerful illustration Paul uses to confront a serious problem in the Galatian churches. It is not merely ancient history.
Some believers in Galatia were being pressured to follow Jewish laws - like circumcision and special religious days - to be truly saved. Paul reminds them that this goes against the gospel. Isaac was born by God's promise, not human effort. We become God's children through faith, not by keeping the law. The law, symbolized by Hagar and Mount Sinai, brings slavery, but the promise, symbolized by Sarah and the Jerusalem above, brings freedom.
So Paul's message is clear: trying to earn God's favor through rules leads to spiritual slavery, but trusting God's promise brings true freedom as heirs of His kingdom.
Two Covenants: Slavery Under Law vs. Freedom Through Promise
Paul dives deep into the story of Hagar and Sarah to expose a fundamental clash between two ways of relating to God: one based on human effort under the law, and the other on divine promise through faith.
He presents Hagar, the slave woman, as representing the covenant from Mount Sinai - the law - which leads to bondage because it depends on what we can do. In contrast, Sarah, the free woman, symbolizes the covenant of promise, where God acts by grace. Isaac was born miraculously to an elderly, barren woman, demonstrating this. This is not merely a historical comparison. Paul calls it an allegory, showing that the law was never meant to give life but to expose sin and point us to God's promise in Christ. As he wrote earlier in Galatians 3:21, 'If a law had been given that could give life, then righteousness would indeed be by the law.'
Paul quotes Isaiah 54:1 - 'Rejoice, O barren one who does not bear; break forth and cry aloud, you who are not in labor!' - to show that the one who seemed spiritually empty (like Sarah) now has more children than the one who relied on human strength. The 'present Jerusalem' tied to Hagar represents a religion of human effort, rules, and external observance, while the 'Jerusalem above' is the spiritual reality of God's grace, where faith produces true offspring. This new covenant fulfills what the old could not: a relationship with God not earned, but freely given.
The conflict between Isaac and Ishmael mirrors the tension believers face today - those living by the Spirit often feel pressure or rejection from those insisting on religious performance. But God's word is clear: '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.'
The law, no matter how holy, cannot produce spiritual life - it only reveals our need for a Savior.
So our identity isn't built on how well we keep rules, but on being children of the promise - born not by fleshly effort, but by the Spirit. This sets the stage for understanding how faith, not works, defines our place in God's family.
Living as Free Children: Freedom in Christ vs. Legalism Today
Now that we've seen how Isaac represents the child of promise and heir of God's grace, the question becomes: how do we live in that freedom without slipping back into religious rule-following?
The Galatians were tempted to think that following laws like circumcision or holy days made them more spiritual, but Paul says that mindset brings slavery - even if the rules seem good. Real faith, the kind that makes us children of the promise, involves trusting God's grace, not external behavior checks. Abraham demonstrated this before any law existed (Genesis 15:6).
True spiritual freedom isn't freedom to do whatever we want, but freedom to live as God's promised children through faith.
This freedom in Christ protects us from both legalism - trying to earn God's love - and license - misusing grace as an excuse to live selfishly - pointing us instead to walk by the Spirit, the true mark of Isaac's spiritual descendants.
Canonical Connections: How Genesis, Isaiah, and Romans Complete the Story
This allegory is rooted in the broader story of Scripture, connecting directly to key moments in Genesis, Isaiah, and Romans. It is not merely Paul's creative interpretation.
Paul's use of Genesis 21:10 - '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' - shows that God has always distinguished between the child of promise and the child of human effort. And when he quotes Isaiah 54:1 - 'Rejoice, O barren one who does not bear; break forth and cry aloud, you who are not in labor!He highlights how God brings life where it seems impossible. He did this for Sarah and now does so spiritually through the gospel.
Later, in Romans 9-11, Paul returns to this theme, explaining that not all physical descendants of Abraham are true heirs - only those of the promise, like Isaac, belong to God’s family, reminding us that our unity as believers rests on grace, not heritage or rules, shaping how we welcome others in the church today.
Application
How This Changes Everything: Real Life Impact
Imagine carrying a backpack full of rules - prayers you must say, behaviors you must perform, spiritual boxes to check - thinking that’s what makes you acceptable to God. That’s the weight of living like Ishmael, born of human effort. But Galatians 4:21-31 lifts that load. When I realized I wasn’t God’s child because I earned it, but because He promised it - like Isaac - I stopped striving and started resting. The guilt of falling short didn’t disappear, but it lost its power. Now, when I fail, I don’t run from God - I run to Him as my Father. And when I succeed, I don’t boast in my performance, but in His promise. That shift from slave to son changes how I parent, work, and even rest - everything flows from grace, not guilt.
Personal Reflection
- Where in my life am I relying on religious habits or moral performance to feel right with God, rather than resting in His promise?
- When have I felt pressure from others - or put it on myself - to prove my faith through rules or rituals?
- How can I encourage someone else this week by reminding them they’re a child of promise, not a spiritual slave?
A Challenge For You
This week, when you feel guilty or spiritually inadequate, speak Galatians 4:28 aloud: 'Now you, brothers, like Isaac, are children of promise.' Replace one rule-based thought with a promise-based truth. And share this truth with one person who feels burdened by religious expectations.
A Prayer of Response
Father, thank You that I’m not Your child because I’ve earned it, but because You promised it. Help me live like Isaac - free, loved, and secure in Your grace. When I’m tempted to return to old rules, remind me that I belong to the Jerusalem above. Free me from trying to prove myself, and fill me with the joy of being Your promised child. In Jesus’ name, Amen.
Related Scriptures & Concepts
Immediate Context
Galatians 4:1-7
Sets the foundation for sonship and inheritance, showing believers are heirs through God’s adoption, not slaves under the law.
Galatians 4:8-11
Highlights the danger of returning to weak religious observances, leading into Paul’s allegory of Hagar and Sarah.
Galatians 4:19-20
Expresses Paul’s pastoral concern, showing his emotional investment before launching into the allegorical argument.
Connections Across Scripture
Genesis 16:1-16
Records the birth of Ishmael through Hagar, illustrating human effort apart from God’s promise, contrasted with Isaac’s miraculous birth.
Isaiah 54:1
Prophetic promise of fruitfulness for the barren, fulfilled in the church as children of the free woman, quoted in Galatians 4:27.
Romans 4:20-21
Highlights Abraham’s faith in God’s promise despite impossibility, reinforcing the theme of promise over flesh in Galatians 4.
Glossary
places
figures
Hagar
Abraham’s servant and mother of Ishmael, symbolizing the old covenant and slavery under the law.
Sarah
Abraham’s wife and mother of Isaac, representing the free covenant of promise and grace.
Isaac
The child of promise, born by God’s power, symbolizing those justified by faith.
Ishmael
The son born by human effort, symbolizing those under the law and natural descent.