WSC Q.34: What is adoption?
Adoption is an act of God’s free grace, (1 John 3:1) whereby we are received into the number, and have a right to all the privileges of the sons of God. (John 1:12, Rom. 8:17)
WLC Q.74: What is adoption?
Adoption is an act of the free grace of God, (1 John 3:1) in and for his only Son Jesus Christ, (Eph. 1:5, Gal. 4:4–5) whereby all those that are justified are received into the number of his children, (John 1:12) have his name put upon them, (2 Cor. 6:18, Rev. 3:12) the Spirit of his Son given to them, (Gal. 4:6) are under his fatherly care and dispensations, (Ps. 103:13, Prov. 14:26, Matt. 6:32) admitted to all the liberties and privileges of the sons of God, made heirs of all the promises, and fellow-heirs with Christ in glory. (Heb. 6:12, Rom. 8:17)
WCF 12.1.
All those that are justified, God vouchsafeth, in and for His only Son Jesus Christ, to make partakers of the grace of adoption, (Eph. 1:5, Gal. 4:4–5) by which they are taken into the number, and enjoy the liberties and privileges of the children of God, (Rom. 8:17, John 1:12) have His name put upon them, (Jer. 14:9, 2 Cor. 6:18, Rev. 3:12) receive the spirit of adoption, (Rom. 8:15) have access to the throne of grace with boldness, (Eph. 3:12, Rom. 5:2) are enabled to cry, Abba, Father, (Gal. 4:6) are pitied, (Ps. 103:13) protected, (Prov. 14:26) provided for, (Matt. 6:30,32, 1 Pet. 5:7) and chastened by Him as by a Father: (Heb. 12:6) yet never cast off, (Lam. 3:31) but sealed to the day of redemption; (Eph. 4:30) and inherit the promises, (Heb. 6:12) as heirs of everlasting salvation. (1 Pet. 1:3–4, Heb. 1:14)