The spirit Himself bears witness with our spirit that we are children of God (Romans 8:16).
For you are all sons of God through faith in Christ Jesus. For all of you who were baptized into Christ have clothed yourselves with Christ (Galatians 3:26, 27).
And because you are sons, God has sent forth the Spirit of His Son into our hearts, crying, “Abba! Father!” Therefore you are no longer a slave, but a son; and if a son, then an heir through God (Galatians 4:6, 7).
But you are a chosen race, a royal priesthood, a holy nation, a people for God’s own possession, that you may proclaim the excellencies of Him who has called you out of darkness into His marvelous light; for you once were not a people, but now you are the people of God; you had not received mercy, but now you have received mercy (1 Peter 2:9, 10).
See how great a love the Father has bestowed upon us, that we should be called children of God; and such we are. . . . Beloved, now we are children of God; and it has not appeared as yet what we shall be. We know that, when He appears, we shall be like Him, because we shall see Him just as He is. And anyone who has this hope fixed on Him purifies himself, just as He is pure (1 John 3:1-3).