What does it mean to be a child of God?
Answer: You become a child of God through adoption. Adoption means that God makes the people He justified His children. Jesus is the only-begotten Son for all eternity, but you became a child of God through adoption because of the work that Jesus did. You became an heir together with Christ to share in the glory that is now His. As a child of God you enjoy an intimacy with God as Father and pray to Him as Father. At times, He also lovingly disciplines you so that you might become more and more like Him in character.
Scripture: But when the right time came, God sent His Son who was born of a woman and lived under the law. God did this so He could buy freedom for those who where under the law and so we could become His children (Galatians 4:4-5). The Spirit Himself bears witness with our spirit that we are the children of God, and if children, then heirs—heirs of God and joint heirs with Christ, if indeed we suffer with Him, that we may also be glorified together (Romans 8:16-17). NKJV