First, two different covenants (21-26). When Abraham and Sarah resigned themselves to childlessness, Abraham took Hagar, a slave woman, and had a son by her. The boy was born according to the flesh. Later God blessed Sarah to have a son, Isaac. He was born according to God's promise. Paul compares Hagar and Sarah to the covenants of law and grace. As Hagar and her children were slaves, so the law produces slavery to the law. But as Isaac was a child of promise, Christians are also children of God's promise in Jesus Christ. Second, you are children of promise (27-31). The Gentile Christians may have been small in number. But they would flourish if they held on to the gospel. (27) As Ishmael persecuted Isaac, (Ge. 21:9) so the false teachers persecuted the genuine Christians. But Paul encouraged the Galatians to remove them from their fellowship. They were a bad influence. The Galatians were not slaves but the free children of God because of Jesus.
Application: Lord, thank you for making us children of your promise. Help me not to be legalistic and purge legalism from among us.
One Word: We are free children of God