The doctrine of adoption is the teaching that man is adopted by God into the family of God. Adoption is the gracious and merciful right (John 1:12) bestowed upon unworthy sinners through which a person is given admission into God’s family. This right is given only to those whom God has justified by faith (Romans 3:28; Galatians 3:24) and has caused to be born again (1 Peter 1:3). God, for reasons known only to Himself and for the purpose of bringing Himself glory, sovereignly (Psalm 37:39; Lamentations 3:26) chose from eternity past (Ephesians 1:5) to miraculously and eternally save those who are by nature children of wrath (Ephesians 2:1-3) and makes them His very own children and co-heirs with His own Son, Jesus Christ (Romans 8:16-17). Spiritual and eternal adoption is solely an act of God and not an act of man (John 1:13).
Adoption is a legal transaction in which God the Father allows those whom He regenerates (2 Corinthians 5:17; Colossians 2:13) and justifies (Romans 8:33) to be allowed into His eternal family (Titus 3:7)--a family they were not a part of prior to their adoption. While regeneration and justification secures one’s salvation from sin and death (Romans 8:2), adoption establishes one’s relationship as a beloved child (Ephesians 5:1) to and with God the Father (Romans 8:15; Galatians 4:6).