Think of it this way. If a father dies and leaves an inheritance for his young children, those children are not much better off than slaves until they grow up, even though they actually own everything their father had.
So now that you know God (or should I say, now that God knows you), why do you want to go back again and become slaves once more to the weak and useless spiritual principles of this world?
Dear brothers and sisters, I plead with you to live as I do in freedom from these things, for I have become like you Gentiles-- free from those laws.You did not mistreat me when I first preached to you.
But even though my condition tempted you to reject me, you did not despise me or turn me away. No, you took me in and cared for me as though I were an angel from God or even Christ Jesus himself.
Those false teachers are so eager to win your favor, but their intentions are not good. They are trying to shut you off from me so that you will pay attention only to them.
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.
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!"
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."