Tell me, you who want to live under the law, do you know what the law actually says? The Scriptures say that Abraham had two sons, one from his slave wife and one from his freeborn wife. The son of the slave wife was born in a human attempt to bring about the fulfillment of God’s promise. But the son of the freeborn wife was born as God’s own fulfillment of his promise.
These two women serve as an illustration of God’s two covenants. The first woman, Hagar, represents Mount Sinai where people received the law that enslaved them. And now Jerusalem is just like Mount Sinai in Arabia, because she and her children live in slavery to the law. But the other woman, Sarah, represents the heavenly Jerusalem. She is the free woman, and she is our mother. As Isaiah said,
“Rejoice, O childless woman,
you who have never given birth!
Break into a joyful shout,
you who have never been in labor!
For the desolate woman now has more children
than the woman who lives with her husband!”
And you, dear brothers and sisters, are children of the promise, just like Isaac. But you are now being persecuted by those who want you to keep the law, just as Ishmael, the child born by human effort, persecuted Isaac, the child born by the power of the Spirit.
But what do the Scriptures say about that? “Get rid of the slave and her son, for the son of the slave woman will not share the inheritance with the free woman’s son.” So, dear brothers and sisters, we are not children of the slave woman; we are children of the free woman.