Listen to me, you who want to live under the law. Do you know what the law really says?
The Scriptures say that Abraham had two sons, one from his slave-wife and one from his freeborn wife.
References for Galatians 4:22
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.
Now these two women serve as an illustration of God's two covenants. Hagar, the slave-wife, represents Mount Sinai where people first became enslaved to the law.
And now Jerusalem is just like Mount Sinai in Arabia, because she and her children live in slavery.
But Sarah, the free woman, represents the heavenly Jerusalem. And she is our mother.
That is what Isaiah meant when he prophesied, "Rejoice, O childless woman! Break forth into loud and joyful song, even though you never gave birth to a child. For the woman who could bear no children now has more than all the other women!"
References for Galatians 4:27
And you, dear brothers and sisters, are children of the promise, just like Isaac.
And we who are born of the Holy Spirit are persecuted by those who want us to keep the law, just as Isaac, the child of promise, was persecuted by Ishmael, the son of the slave-wife.
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 family inheritance with the free woman's son."
References for Galatians 4:30
So, dear brothers and sisters, we are not children of the slave woman, obligated to the law. We are children of the free woman, acceptable to God because of our faith.