Galatians 4:21-31, The Analogy From Hagar and Sarah

When Sarah failed to have a child by Abraham, she cajoled him into taking her slave girl, Hagar, as wife, and the child born to her, Ishmael, belonged to Sarah and Abraham, according to the custom of that day. But God still planned for Sarah to have her own child as promised, and when Isaac was born, he took precedence over Ishmael. When Ishmael mocked Isaac one day, Sarah had enough. God told Abraham to let Sarah do as she would, and Sarah sent Hagar and Ishmael packing. For Paul, this served as an analogy to what was happening in Galatia.

21 Tell me, those of you desiring to be under the law, are you paying attention to the law? 22 For it is written that Abraham had two sons, one from the slave girl and one from the free woman. 23 But the one from the slave girl was born by human engineering, and the one from the free woman was born through promise. 24 These things are an analogy. These represent two covenants, one from Mount Sinai giving birth to slavery, which is Hagar. 25 For Hagar represents Mount Sinai in Arabia, which corresponds with present day Jerusalem, for she is enslaved there with her children. 26 But the Jerusalem from above is free, which represents us. 27 For it is written, “Be glad, barren woman, who has not given birth, burst forth and call out, you who have not had birth pains, because more are the children of the desolate one than of she who has a husband.” 28 Now you, brothers and sisters, like Isaac, are children of promise. 29 But as the one born of human engineering persecuted the one born according to the Spirit, so it is now. 30 Yet it is written, “Cast out the slave girl and her son, for the son of the slave girl is not an heir with the son of the free woman. 31 For this reason, brothers and sisters, we are not children of the slave girl, but of the free woman. (Galatians 4:21-31)

Two covenants, the Law of Moses and the Covenant of Promise with Abraham, are represented by Hagar and Sarah and their offspring. Mount Sinai is where the law was given, and Jerusalem is where its adherents center. The heavenly Jerusalem, which furnished the pattern for the tabernacle and the temple (Exodus 25:40; Hebrews 8:5), represents the covenant of promise with Abraham and Sarah’s offspring, Isaac, the child of promise. Hagar’s child came about by human endeavor, Isaac by miracle. The one is a child of slavery, the other is like the Jerusalem above, free. Once again,

Such an association would have been shocking to the Judaizers and to all Jews. To think that Paul would say that those who “obey the law” are for that very reason in the line of Ishmael! (NIV Life Application Commentary)

Paul then quotes from Isaiah 54:1, which is a prophecy of Isaiah concerning Jerusalem’s restoration as Israel returns from captivity, using the promise given Jacob that he would spread out and dispossess nations (54:3). In effect, this has happened with the preaching of Paul’s gospel, as many more than the slave girl’s children have believed the gospel and been born into God’s kingdom.

But like then, the slave woman’s child persecutes the free woman’s child and must be cast out. The false teachers are carrying on the same persecution Ishmael did against Isaac, the slave against the free, and must be cast out. The Galatians are not children of the slave but of the free. They must claim their freedom.