Think of it this way. If a father dies and leaves great wealth 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.
They have to obey their guardians until they reach whatever age their father set.
And that's the way it was with us before Christ came. We were slaves to the spiritual powers of this world.
But when the right time came, God sent his Son, born of a woman, subject to the law.
God sent him to buy freedom for us who were slaves to the law, so that he could adopt us as his very own children.
And because you Gentiles have become his children, God has sent the Spirit of his Son into your hearts, and now you can call God your dear Father.
Now you are no longer a slave but God's own child. And since you are his child, everything he has belongs to you.
Before you Gentiles knew God, you were slaves to so-called gods that do not even exist.
And now that you have found God (or should I say, now that God has found you), why do you want to go back again and become slaves once more to the weak and useless spiritual powers of this world?
You are trying to find favor with God by what you do or don't do on certain days or months or seasons or years.
I fear for you. I am afraid that all my hard work for you was worth nothing.
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 were--free from the law. You did not mistreat me when I first preached to you.
Surely you remember that I was sick when I first brought you the Good News of Christ.
But even though my sickness was revolting to you, you did not reject me and 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.
Where is that joyful spirit we felt together then? In those days, I know you would gladly have taken out your own eyes and given them to me if it had been possible.
Have I now become your enemy because I am telling you the truth?
Those false teachers who are so anxious to win your favor are not doing it for your good. They are trying to shut you off from me so that you will pay more attention to them.
Now it's wonderful if you are eager to do good, and especially when I am not with you.
But oh, my dear children! I feel as if I am going through labor pains for you again, and they will continue until Christ is fully developed in your lives.
How I wish I were there with you right now, so that I could be more gentle with you. But at this distance I frankly don't know what else to do.
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.
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!"
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."
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.