Growing up in Mississippi, my family moved around a lot — but there was always one place that felt like home: my grandparents’ house. My grandfather was a deacon at First Baptist, my grandmother taught Sunday school for decades, and between the two of them, it seemed like everybody in that small town knew them. So whenever I’d walk into the Piggly Wiggly as a boy and someone recognized me, they’d ask the same question every time: “Whose boy are you?”The second I said my mother’s name, they knew exactly who I belonged to. I didn’t earn that. It was my mother’s name before I was ever born.
That question — whose boy are you? — sits at the heart of Galatians 4:21-31. Paul is about to look at a room full of religious people who are very confident they know who their father is. And he’s going to ask them something they never saw coming: Who is your mother?
The History (Galatians 4:21-23)
Paul addresses those who “desire to be under the law” — not those who already are, but those who are being tempted to add rule-keeping to their faith in Christ. His argument is sharp: if you want to submit to the law, then listen to what the law actually says. And what it says begins with Abraham.
Abraham had two sons. One by Hagar, a slave woman. One by Sarah, a free woman. The difference between these two boys wasn’t in what they did — it was in how they were born. Ishmael was born “according to the flesh,” the product of Abraham and Sarah’s impatience with God’s timing. When God’s promise seemed slow, they took matters into their own hands, and what resulted was sin. Isaac, on the other hand, was born “through promise” — to a father who was 100 years old and a mother who was 90 and had never conceived. Nothing in nature said that was possible. It was supernatural. It was God’s way.
The birth of Ishmael represents the human way — flesh, effort, impatience. The birth of Isaac represents God’s way — promise, grace, the impossible made possible.
The Interpretation (Galatians 4:24-27)
Paul then does something striking: he tells us this history carries an allegorical meaning. He is careful to note that the Genesis story is true history — real people, real events. But under the inspiration of the Holy Spirit, Paul is able to show us what God intended this history to teach. These two women, he says, represent two covenants. Hagar and Ishmael correspond to the covenant of law used for works — it bears children into slavery. Sarah and Isaac correspond to the covenant of grace received by faith — it bears children into freedom.
Then Paul says something that would have been fighting words to his original audience: Hagar corresponds to the present Jerusalem. In other words, those who are still trying to earn their standing before God by keeping the law — whatever their religious pedigree — are not from Sarah’s side. They are from Hagar’s. They are Ishmael, not Isaac.
But the Jerusalem above, Paul says, is free — and she is our mother. He doesn’t say “the Jerusalem to come.” He says above, meaning presently. Salvation is not only something that is coming someday; it has already reached down into right now. The free woman is still bearing children through the preaching of the Word, and God is not finished giving birth.
Paul’s Application (Galatians 4:28-31)
Paul lands the argument in three moves. First, he affirms his readers: you, brothers, like Isaac, are children of promise.You didn’t earn that. You were born into it by grace. Second, he prepares them: just as Ishmael persecuted Isaac at his own birthday feast — a 17-year-old mocking a 3-year-old — so children of promise should expect to be mocked and opposed, even by religious people. The pressure to add something to Christ for your salvation has never gone away. Third, he quotes Genesis directly: “Cast out the slave woman and her son, for the son of the slave shall not inherit with the son of the free woman.” The law itself — the very thing the legalists were clinging to — says cast out the slave. The law rejects the law as a means of salvation.
The conclusion is this: we are not children of the slave. We are children of the free woman.
Applying It
Read God’s Word wide and deep. To understand what Paul is saying in Galatians 4, you have to go back to Genesis 16 and 21. The Bible rewards people who read it thoroughly — not just surface-level application, but digging into the original context. A good study Bible or a free resource like Blue Letter Bible will open up the text in ways a casual reading never will.
Your sin affects others more than you know. Abraham and Sarah’s impatient decision to go to Hagar set off a chain of consequences they could never have anticipated — for Hagar, for Ishmael, and four thousand years later, for a conflict still playing out in the Middle East. We never sin in a vacuum. But here is the other side of that truth: Abraham’s sin never once canceled God’s faithfulness. He still kept His promise. The consequences of sin are real — and the grace of God is bigger than your worst decision.
You must be born again. The difference between Ishmael and Isaac was never about behavior. It was about birth. You cannot earn your way into the family of God, and you cannot behave your way there either. The only way in is to be born again — by grace alone, through faith alone, in Christ alone. God is holy; we are sinful; our sin separates us from Him; but Jesus lived the life we couldn’t live, died the death we deserved, and rose again on the third day. If you turn from your sin and trust Him as both Savior and Lord, you will be born into the family of the free woman.
You may have walked in trying to earn it. You can walk out resting in it.
