Paul shows the Galatians that living under the law is slavery, but living by faith in Christ is freedom. Christ reconciled us to God, making us sons and heirs of His promise. Paul reminds the Galatians of the personal history they’ve shared. In the past, they treated Paul with reverence and love, and now they are treating him like an enemy by ignoring his teaching and submitting to the competing Jewish “authorities.” Paul quotes the Old Testament to show the allegory of children of slavery and children of the promise: Abraham had two sons, Ishmael and Isaac. Ishmael was the son of a slave woman and was not an inheritor of God’s promises, while Isaac was the legitimate son of Abraham’s wife—a free woman. Believers in Jesus are free sons of God’s promise, not slaves to law-following or religious rituals.