What is adoption?

Answer

Adoption is an act of God's free grace (), whereby we are received into the number and have a right to all the privileges of the sons of God (; ).

Read the 3 proof texts (KJV)

1 John 3:1: Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not.
John 1:12: But as many as received him, to them gave he power to become the sons of God, [even] to them that believe on his name:
Romans 8:14-17: ¹⁴For as many as are led by the Spirit of God, they are the sons of God. ¹⁵For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. ¹⁶The Spirit itself beareth witness with our spirit, that we are the children of God: ¹⁷And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with [him], that we may be also glorified together.