Let me explain further. As long as an heir is a child, he is no better off than a slave, even though he owns everything.
He is placed under the control of guardians and trustees until the time set by his father.
It was the same way with us. When we were children, we were slaves to the principles of this world.
But when the right time came, God sent his Son [into the world]. A woman gave birth to him, and he came under the control of God's laws.
God sent him to pay for the freedom of those who were controlled by these laws so that we would be adopted as his children.
Because you are God's children, God has sent the Spirit of his Son into us to call out, "Abba! Father!"
So you are no longer slaves but God's children. Since you are God's children, God has also made you heirs.
When you didn't know God, you were slaves to things which are really not gods at all.
But now you know God, or rather, God knows you. So how can you turn back again to the powerless and bankrupt principles of this world? Why do you want to become their slaves all over again?
You religiously observe days, months, seasons, and years!
I'm afraid for you. Maybe the hard work I spent on you has been wasted.
Brothers and sisters, I beg you to become like me. After all, I became like you were. You didn't do anything wrong to me.
You know that the first time I brought you the Good News I was ill.
Even though my illness was difficult for you, you didn't despise or reject me. Instead, you welcomed me as if I were God's messenger or Christ Jesus himself.
What happened to your positive attitude? It's a fact that if it had been possible, you would have torn out your eyes and given them to me.
Can it be that I have become your enemy for telling you the truth?
These people [who distort the Good News] are devoted to you, but not in a good way. They don't want you to associate with me so that you will be devoted only to them.
(Devotion to a good cause is always good, even when I'm not with you.)
My children, I am suffering birth pains for you again until Christ is formed in you.
I wish I were with you right now so that I could change the tone of my voice. I'm completely puzzled by what you've done!
Those who want to be controlled by Moses' laws should tell me something. Are you really listening to what Moses' Teachings say?
Scripture says that Abraham had two sons, one by a woman who was a slave and the other by a free woman.
Now, the son of the slave woman was conceived in a natural way, but the son of the free woman was conceived through a promise [made to Abraham].
I'm going to use these historical events as an illustration. The women illustrate two arrangements. The one woman, Hagar, is the arrangement made on Mount Sinai. Her children are born into slavery.
Hagar is Mount Sinai in Arabia. She is like Jerusalem today because she and her children are slaves.
But the Jerusalem that is above is free, and she is our mother.
Scripture says: "Rejoice, women who cannot get pregnant, who cannot give birth to any children! Break into shouting, those who feel no pains of childbirth! Because the deserted woman will have more children than the woman who has a husband."
Now you, brothers and sisters, are children of the promise like Isaac.
Furthermore, at that time the son who was conceived in a natural way persecuted the son conceived in a spiritual way. That's exactly what's happening now.
But what does Scripture say? "Get rid of the slave woman and her son, because the son of the slave woman must never share the inheritance with the son of the free woman."
Brothers and sisters, we are not children of a slave woman but of the free woman.