What I am saying is that as long as an heir is underage, he is no different from a slave, although he owns the whole estate. The heir is subject to guardians and trustees until the time set by his father. So also, when we were underage, we were in slavery under the elemental spiritual forces of the world. But when the set time had fully come, God sent his Son, born of a woman, born under the law, to redeem those under the law, that we might receive adoption to sonship. Because you are his sons, God sent the Spirit of his Son into our hearts, the Spirit who calls out, “Abba, Father.” So you are no longer a slave, but God’s child; and since you are his child, God has made you also an heir.
Galatians 4:1-7 (NIV)