1What I am saying is that as long as the heir is a child, he is no different from a slave, although he owns the whole estate. 2He is subject to guardians and trustees until the time set by his father. 3So also, when we were children, we were in slavery under the basic principles of the world. 4But when the time had fully come, God sent his Son, born of a woman, born under law, 5to redeem those under law, that we might receive the full rights of sons. 6Because you are sons, God sent the Spirit of his Son into our hearts, the Spirit who calls out, "Abba,[a] Father." 7So you are no longer a slave, but a son; and since you are a son, God has made you also an heir.
Verse 6 is what has been going over and over in my mind. "God sent the Spirit of his Son (the Holy Spirit) into our hearts". So the Holy Spirit is a part of us and indwells in us. Then the cool part..."the Spirit who calls out, "Abba, Father". So we have the Holy Spirit in our hearts and the Holy Spirit cries out "Abba Father!" For me, it makes sense why we have this natural draw or longing for our heavenly father. We have the holy spirit within us who is crying out for Him!