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. 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 like children; we were slaves to the basic spiritual principles 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 we are his children, God has sent the Spirit of his Son into our hearts, prompting us to call out, “Abba, Father.” Now you are no longer a slave but God’s own child. And since you are his child, God has made you his heir.