Galatians 4:28-31 meaning

Paul doubles down on his allegory, comparing the competing Jewish "authorities" and law-following to slavery, or to being like a child of the slave, Hagar. But believers are, in reality, like Isaac, children of promise. Isaac was the child God had promised to Abraham, born of the free woman Sarah, not the slave woman Hagar.

Paul points to the parallel between Hagar's son Ishmael persecuting Isaac and the competing Jewish "authorities" persecuting Paul. The competing Jewish "authorities" are teaching the Galatians to become Jews, to follow the law, because that is how they think they gain righteousness before God. This is a human, earthly way of trying to control God, like Abraham giving himself an heir from a slave woman, rather than his wife. Isaac, the son of promise, the true heir, is the symbol for believers. We "belong to Christ... Abraham's descendants, heirs according to promise" (Galatians 3:29). All of Paul's references and illustrations point to believers as free people, inheritors of God's promises, not slaves. The competing Jewish "authorities" and Galatians are practicing spiritual slavery by thinking that following the law makes them justified in God's eyes.

Paul gives the Galatians a solution. He tells the Galatians to stop their persecution from the competing Jewish "authorities" the same way Abraham dealt with Ishmael's persecution of Isaac. He quotes Genesis 21:10, Cast out the bondwoman and her son. Paul exhorts the Galatians to terminate their relationship with the competing Jewish "authorities." This is the prescription the Bible gives to deal with false teaching—get rid of it.

The method of these competing Jewish "authorities" is to follow the law to please God. But it doesn't work. It is the opposite of living the resurrection life of Christ; it is slavery. Also, it goes nowhere: the son of the bondwoman shall not be an heir with the son of the free woman. There is no reward in following the law, not in the future kingdom of Christ nor in our present life on this earth. There is only the illusion of righteousness.

Paul concludes his argument by again pointing to our identity as believers. We are brethren who are not children of a bondwoman, but of a free woman. Living with daily faith in Christ is freedom. We experience the blessings of God through faith. We mature in our faith, Christ is formed in us (Gal 4:19) when we live by faith, not by following rules or rituals. When Christ set us free, He set us free from the Law.