Paul calls the Galatians foolish for turning back to the law. He asks whether they received the Spirit by works of the law or by hearing with faith. Having begun by the Spirit, they cannot be made complete by human effort.

Paul points to Abraham, who believed God, and it was credited to him as righteousness. Those who have faith are children of Abraham. The Scripture foretold that God would bless the nations through Abraham. Those who rely on the law are under a curse, because no one keeps it perfectly. Christ redeemed believers from that curse by taking it on Himself, so that Abraham's blessing could reach the Gentiles.

God's promise to Abraham came 430 years before the law, so the law cannot cancel it. The law was added because of sin, until the promised offspring, Christ, would come. It was like a guardian watching over children until faith arrived. Now all believers are children of God through faith in Christ. In Christ there is neither Jew nor Greek, slave nor free, male nor female. All are one, Abraham's offspring and heirs of the promise.

Paul's argument moves from experience to Scripture. He reminds the foolish Galatians that Christ crucified was vividly portrayed before them. They received the Spirit by hearing with faith, not by works of the law. Having begun by the Spirit, would they now seek completion by the flesh? God supplies the Spirit and works miracles among them through faith.

Abraham believed God, and it was credited to him as righteousness, citing Genesis 15:6. Therefore those of faith are Abraham's true children. Scripture foresaw that God would justify the Gentiles by faith, announcing beforehand that all nations would be blessed in Abraham. All who rely on works of the law are under a curse, for the law demands complete obedience, while Habakkuk 2:4 says the righteous will live by faith. Christ redeemed believers from the curse of the law by becoming a curse for them, as Deuteronomy 21:23 describes one who hangs on a tree. So the blessing of Abraham comes to the Gentiles, and believers receive the promised Spirit through faith.

A covenant once ratified cannot be annulled, and the promise to Abraham and his offspring, singular, points to Christ. The law, coming 430 years later, cannot void it. The law was added because of transgressions until the offspring came, and it served as a guardian, like a household slave who supervised children until they came of age. Now that faith has come, believers are no longer under a guardian. They are all sons of God through faith, having been baptized into Christ and clothed with Him. Ethnic, social, and gender distinctions no longer determine standing before God, for all are one in Christ Jesus and heirs according to the promise.