Now are we the sons of God, and it doth not yet appear what we shall be —1 John 3:2
This is one of those Bible doctrines that falls into the unfathomable category. Just think about Who we are talking about being sons of, we are speaking of the Creator of all things Himself. He has brought us into His very own family, into a fellowship that the Heavenly Father and the uncreated Son of God have enjoyed from eternity. The ramifications are unthinkable. We were once enemies of God, children of darkness, until God’s only Son became one of us. He purchased us with His own blood and the results; He has sent the Spirit of Sonship into our hearts. This is more than just a legal adoption, He has come to live inside of us making us essentially one with HIm. This is too good to be true. Here is how A. B. Simpson sees this verse.
“We are the sons of God. We are not merely called such or even legally declared so, but we actually are sons of God by receiving the life and nature of God. And so we are the very brethren of our Lord, not only in His human nature, but still more so in His divine relationship. Therefore, he is not ashamed to call [us] brethren. He gives us that which entitles us to that right, and makes us worthy of it. He does not introduce us into a position for which we are uneducated and unfitted, but He gives us a nature worthy of our glorious standing; and as He shall look upon us in our complete and glorious exaltation-reflecting His own likeness and shining in His Father’s glory-He shall have no cause to be ashamed of us. Even now He is pleased to acknowledge us before the universe and call us brethren in the sight of all earth and heaven. Oh, how this dignifies the humblest saint of God! How little we need mind the misunderstanding of the world if He is not ashamed to call [us] brethren.”
What is the privilege of being family? It is access, fellowship with God. Jesus described this in His final prayer, He prayed that we could enjoy the intimacy with the Father that He had enjoyed from eternity. This is our inheritance, fellowship with God. This is why Jesus came, this is what He purchased with His own blood.