Adoption, as a Biblical term, occurs only in the New Testament. In Old Testament history the practice was unknown, though cases approximating to it have been pointed out. In the New Testament υ ἱ o θ ∈ σ ί α occurs in several passages, on which is founded one of the leading doctrines of theology.

Adoption in a theological sense is that act of God’s free grace by which, upon our being justified by faith in Christ, we are received into the family of God, and entitled to the inheritance of heaven. This appears not so much a distinct act of God, as involved in, and necessarily flowing from, our justification; so that, at least the one always implies the other. Nor is there any good ground to suppose that in the New Testament the term adoption is used with any reference to the civil practice of adoption by the Greeks, Romans, or other Heathens, and therefore it is not judicious to illustrate the texts in which the word occurs by their formalities. The Apostles in using the term appear to have had before them the simple view, that our sins had deprived us of our sonship, the favour of God, and the right to the inheritance of eternal life; but that, upon our return to God, and reconciliation with him, our forfeited privileges were not only restored, but greatly heightened through the paternal kindness of God. They could scarcely be forgetful of the affecting parable of the prodigal son; and it is under the same view that St. Paul quotes from the Old Testament, “Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing, and I will receive you, and I will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty.” Adoption, then, is that act by which we who were alienated, and enemies, and disinherited, are made the sons of God, and heirs of his eternal glory. “If children, then heirs, heirs of God and joint heirs with Christ;” where it is to be remarked, that it is not in our own right, nor in the right of any work done in us, or which we ourselves do, though it should be an evangelical work, that we become heirs; but jointly with Christ, and in his right.

To this state belong, freedom from a servile spirit, for we are not servants but sons; the special love and care of God our heavenly Father; a filial confidence in him; free access to him at all times and in all circumstances; a title to the heavenly inheritance; and the Spirit of adoption, or the witness of the Holy Spirit to our adoption, which is the foundation of all the comfort we can derive from those privileges, as it is the only means by which we can know that they are ours.

The last mentioned great privilege of adoption merits special attention. It consists in the inward witness or testimony of the Holy Spirit to the sonship of believers, from which flows a comfortable persuasion or conviction of our present acceptance with God, and the hope of our future and eternal glory. This is taught in several passages of Scripture:-- Rom. viii, 15, 16, “For ye have not received the spirit of bondage again to fear, but the Spirit of adoption, whereby we cry, Abba, Father. The Spirit itself beareth witness with our spirit that we are the children of God.” In this passage it is to be remarked, 1. That the Holy Spirit takes away “fear,” a servile dread of God as offended. 2. That the “Spirit of God” here mentioned, is not the personified spirit or genius of the Gospel, as some would have it, but “the Spirit itself,” or himself, and hence he is called in the Galatians, “the Spirit of his Son,” which cannot mean the genius of the Gospel. 3. That he inspires a filial confidence in God, as our Father, which is opposed to “the fear” produced by the “spirit of bondage.” 4. That he excites this filial confidence, and enables us to call God our Father, by witnessing, bearing testimony with our spirit, “that we are the children of God.” Gal. iv, 4–6, “But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law, to redeem them that were under the law, that we might receive the adoption of sons; and because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.” Here also are to be noted, 1. The means of our redemption from under (the curse of) the law,--the incarnation and sufferings of Christ. 2. That the adoption of sons follows upon our actual redemption from that curse, or, in other words, upon our pardon. 3. That upon our being pardoned, the “Spirit of the Son” is “sent forth into our hearts,” producing the same effect as that mentioned in the Epistle to the Romans, viz. filial confidence in God,--“crying, Abba, Father.” To these texts are to be added all those passages, so numerous in the New Testament, which express the confidence and the joy of Christians; their friendship with God; their confident access to him as their God; their entire union and delightful intercourse with him in spirit. This has been generally termed the doctrine of assurance, and, perhaps, the expressions of St. Paul, “the full assurance of faith,” and “the full assurance of hope,” may warrant the use of the word. But as there is a current and generally understood sense of this term, implying that the assurance of our present acceptance and sonship implies an assurance of our final perseverance, and of an indefeasible title to heaven; the phrase, a comfortable persuasion, or conviction of our justification and adoption, arising out of the Spirit’s inward and direct testimony, is to be preferred. There is, also, another reason for the sparing and cautious use of the term assurance, which is, that it seems to imply, though not necessarily, the absence of all doubt, and shuts out all those lower degrees of persuasion which may exist in the experience of Christians. For, our faith may not at first, or at all times, be equally strong, and the testimony of the Spirit may have its degrees of clearness. Nevertheless, the fulness of this attainment is to be pressed upon every one: “Let us draw near,” says St. Paul to all Christians, “with full assurance of faith.” It may serve, also, to remove an objection sometimes made to the doctrine, and to correct an error which sometimes pervades the statement of it, to observe that this assurance, persuasion, or conviction, whichever term be adopted, is not of the essence of justifying faith; that is, justifying faith does not consist in the assurance that I am now forgiven, through Christ. This would be obviously contradictory. For we must believe before we can be justified; much more before we can be assured, in any degree, that we are justified:--this persuasion, therefore, follows justification, and is one of its results. But though we must not only distinguish, but separate, this persuasion of our acceptance from the faith which justifies, we must not separate it, but only distinguish it, from justification itself. With that come in as concomitants, adoption, the “Spirit of adoption,” and regeneration.