Having set forth the truth that the state of righteousness in God’s sight cannot be achieved by means of human works but is God’s gift, the apostle now, in harmony with 4:21, elaborates on the fact that this representation is not a novelty but is thoroughly scriptural.
In this connection he fixes the attention of the hearer and/or reader on the manner in which Abraham obtained this great blessing: “Abraham believed God, and it was reckoned to him for righteousness” (Gen. 15:6). He comments, “Now to the one who works, his wages are not reckoned as a favor but as a debt. On the other hand, to the person who does not work but rests his faith on him who justifies the ungodly, his faith is reckoned for righteousness.” God counted for righteousness that which Abraham appropriated by faith, namely, the righteousness of Another, that is, of Jesus Christ, which was imputed to Abraham. Cf. Rom. 4:6, 11, 25; 5:6-21; cf. Isa. 53:4-6, 8, 12.
By means of a quotation from Ps. 32 the apostle proves that what was true with respect to Abraham holds for all believers: “Blessed (are) those whose transgressions are forgiven, whose sins are covered.”
Returning to Gen. 15:6, Paul asks, “Is this blessing then pronounced only upon the circumcised or also upon the uncircumcised?” He shows that it was long before Abraham was circumcised that his faith was reckoned for righteousness. As a result Abraham became “the father of all believers”; that is, of those uncircumcised as well as of those circumcised; in other words, of Gentile as well as of Jewish believers (verses 1-12).
In close connection with the immediately preceding, Paul now emphasizes the importance of God’s promise and its fulfilment. It was not through the law that Abraham received the promise. Human works or merit had nothing to do with it. It was faith in the promise that mattered. Cf. Gal. 3:9, 29. God promised Abraham that he would be “the father of many nations,” therefore “heir of the world” (Gen. 17:5). Abraham did not waver in unbelief but was strengthened in faith. He rested his faith on him “who imparts life to the dead, and calls things that are not as though they were.” In view of the fact that Abraham was almost a hundred years old and Sarah was barren, this faith of Abraham was indeed remarkable. The patriarch believed that whatever God promised he would also do. Moreover, the words “It was reckoned to him for righteousness” were meant not only for him but for all who rest their faith on God, the One who “raised Jesus our Lord from the dead.”
The Savior “was delivered up for our trespasses and was raised for our justification.” This probably means that our trespasses made it necessary for Jesus to be delivered over to death, and that he was raised to life in order to assure us that his vicarious sacrifice had been accepted. As a result believers are, in the very sight of God, without sin and therefore righteous (verses 13-25).
By means of corroborative evidence from the Old Testament Paul has made clear that the comforting doctrine of justification-hence salvation-by faith, on the basis of God’s sovereign grace, is indeed thoroughly scriptural.