Galatians 4 shows that both legalism and idolatry are forms of spiritual slavery that reject the freedom found in Christ. Paul uses the image of a child-heir under a guardian to illustrate that, before faith, people are enslaved to “elementary principles”—whether the Jewish law or pagan gods. But when Christ came, he redeemed us, adopted us, and sent his Spirit into our hearts so that we cry “Abba, Father.” Christians are not slaves but sons, and we are called to live out that sonship through knowing the truth, praying as children to our Father, and serving others in love—rejecting anything that would pull us back into trying to earn what has already been freely given.

God’s promise to Abraham was a gift of grace, not something earned through effort. When the law came centuries later, it didn’t cancel or replace that promise—it revealed just how much we need it. The law exposed our sin and humbled us, like a stern tutor preparing us for the arrival of Christ. But now that Christ has come, we are no longer under the law—we are adopted as God’s children through faith, fully loved and fully accepted. In Jesus, we are united, made heirs of a rich inheritance that includes not only forgiveness and the Spirit now, but the whole world to come. From beginning to end, our standing with God rests not on what we do, but on what Christ has done.

In Galatians 3:1–6, Paul confronts the Galatians for drifting from the gospel of grace, reminding them that they received the Spirit not by works but by “hearing with faith.” This sermon emphasizes that the Christian life—both its beginning and its continuation—is entirely dependent on God’s grace, received through faith. Good works are not the cause of salvation, but the result of it. Christians must resist the temptation to rely on self-effort and instead daily return to the gospel, trusting in the Spirit’s power for sanctification.

Paul confronts Peter for acting in a way that misrepresents the gospel, reminding us that justification is by faith in Christ alone—not by works or law-keeping. When we misuse God’s law as a means of righteousness, we not only mislead others but also obscure the good news of grace. The law functions like a mirror, showing our need for Christ, while only Christ can make us righteous. Justification is a gift received, not earned or maintained through human effort.

Instead of opening this letter to the Galatian churches with a thanksgiving for them — as Paul normally does — he begins by stating that he is astonished that they are so quickly deserting Jesus. The Galatians didn’t think that they had deserted Jesus! But Paul labors for Christ formed in them through the book of Galatians by demonstrating that departing from true gospel doctrine is deserting Jesus himself. In these first handful of verses, Paul sets out the terms of true gospel doctrine.