Although the Church existed from the beginning, it was, before the calling of Abraham, for the most part in a state of dispersion. Too little is recorded of it, prior to that event, to give us definite knowledge of its nature and requirements. Our written constitution, so to speak, dates from the father of the faithful. God made a covenant with Abraham. By covenant is meant, a contract between two or more parties, in which there are mutual stipulations and promises. The transaction with Abraham was of this kind. God promised certain blessings to the patriarch, and he promised faith and obedience to God. Not only, therefore, in the Old Testament is this transaction called a covenant, but in the New Testament the same designation is applied to it. And, further than this, the New Testament writers, referring to the transaction with Abraham, not only call it a covenant, but they argue from its nature as such, to show that its original stipulations can be neither annulled nor altered. Rom. 4:13, 14; Gal. 3:15–18. “The covenant,” says the apostle, “that was confirmed before (to Abraham) of God in Christ, the law, which was four hundred and thirty years after, cannot disannul.” It is of importance, therefore, that this word should be retained, not only because it is scriptural, but because the idea which it expresses is essential to a proper understanding of the case. Many modern theological writers discard the word entirely, and stigmatize the system of the Reformers as the federal theology. In discarding the word, the truth which it was intended to convey is almost always discarded with it. If we would retain the truth, we must retain the forms in which God has seen fit to reveal it. God then formed a covenant with Abraham. The question is, What was that covenant, and who were the parties to it? We answer, in common with all Christendom, The covenant was the covenant of grace, and the parties were Abraham and those whom Abraham represented. Of course this does not mean that the covenant of grace originated in this transaction, or that none are included in it but Abraham and those whom Abraham represented. Nor does it mean that all represented by Abraham were savingly interested in its benefits. It only means that the covenant in question was a reënactment or renewed revelation of the covenant of grace in relation to Abraham, and that those represented by him were to be regarded and treated as included in it.
By the covenant of grace is meant the plan of salvation, in which God promises to give to believers all the benefits of redemption, and they promise faith and obedience. If, therefore, in the covenant with Abraham, God promised to him the benefits of redemption on the condition of faith, that covenant was the covenant of grace. In other words, it was the gospel; for the gospel is nothing else than the proclamation of salvation through faith in Christ. That such was the nature of the covenant made with Abraham, is too clearly revealed to admit of doubt. When God promised that in his seed all the nations of the earth should be blessed, he promised to send Christ to be the Redeemer of men. It is the fulfilment of this promise and the exposition of it in the New Testament, which authoritatively determines its meaning. Our Lord himself said, “Abraham saw my day and was glad.” This can only mean that Abraham foresaw the advent of Christ, and rejoiced in the accomplishment of the work which Christ came to perform. The apostle therefore says, “God preached before the gospel unto Abraham.” The gospel, in the New Testament sense of the term, is the glad news of salvation through Jesus Christ. This therefore was, according to the apostle, what was preached to Abraham, when it was said, “In thee shall all nations be blessed.” The apostle Peter also, after he had healed the lame man, told the astonished multitude that Christ, in whose name the miracle had been performed, had been promised to Abraham, and predicted by the prophets. “Ye,” he added, “are the children of the prophets, and of the covenant which God made with our fathers, saying unto Abraham, And in thy seed shall all the kindreds of the earth be blessed. Unto you first, God having raised up his Son Jesus, sent him to bless you, in turning away every one of you from his iniquities.” Acts 3:25, 26. It is here clearly taught that the Abrahamic covenant, of which the Jews were the children, had reference to Christ; that the promise, “In thy seed shall all the kindreds of the earth be blessed,” was fulfilled in the advent of the Son of God; and that the blessedness promised, was turning men from their iniquities. To the same effect Paul said in the synagogue at Antioch, in Pisidia, “We declare unto you glad tidings, how that the promise made unto the fathers, God hath fulfilled the same unto us their children, in that he hath raised up Jesus.” Acts 13:32, 33. When arraigned before Agrippa he said, “Now I stand and am judged for the hope of the promise made unto our fathers: unto which promise the twelve tribes, instantly serving God day and night, hope to come: for which hope’s sake, king Agrippa, I am accused of the Jews.” Acts 26:6, 7. The great promise made to Abraham and to the other fathers, according to this passage, was the promise of Christ, on whose behalf Paul was a prisoner; and this was the promise toward which the eyes of all who served God were constantly fixed. Paul said to the Romans, “Jesus Christ was a minister of the circumcision, for the truth of God, to confirm the promises made unto the fathers.” Rom. 15:9. That is, Jesus Christ came and exercised his ministry among the Jews, to set forth the truth or veracity of God, in fulfilling the promises made to the fathers. In all these passages, “the promises made to the fathers,” means the promise of Christ thrice made to Abraham, Gen. 12:3, 18:18, 22:18, repeated to Isaac and Jacob, Gen. 26:4, 28:14, and which thenceforth became the burden of prophecy, renewed to every generation, constantly unfolded in its inexhaustible contents until the fulfilment came. Nothing, therefore, can be plainer than that the covenant made with Abraham was the covenant of grace, i.e. the promise of redemption through faith in the Messiah. This, however, is not a doctrine which rests on such general allusions or declarations merely, it is taught in the most explicit terms by the apostles. The design of the epistle to the Galatians was to convince them of the folly of apostatizing to Judaism. To do this the apostle raises them above the Mosaic period, and sets them back into communion with the great Abrahamic covenant, to which the law of Moses was not only posterior but subordinate. The special purpose of the third chapter of that epistle is to prove that justification is by faith, and not by the law. His first argument is from the fact that the Holy Ghost, in his manifold miraculous and sanctifying influences, had been given in confirmation of the doctrine of justification by faith. His second argument is from the case of Abraham. He was justified by faith, and therefore those who share his inheritance, i.e. who inherit the blessing of redemption promised him, are believers. Know therefore, he says, that believers are the sons (i.e. heirs) of Abraham. The third argument is from the impossibility of rendering the perfect obedience which the law demands. The fourth, from the explicit declaration of the Scriptures, that those who are just by faith shall live. The fifth, from the fact that Christ has redeemed us from the curse of the law in order that the blessing of Abraham, (i.e. the blessing promised to Abraham,) might come upon the gentiles. The only blessing, however, promised to Abraham, which comes upon the gentiles, is redemption. And finally, Paul argues from the nature of the covenant made with Abraham. He reminds his readers that even a human covenant cannot, when once ratified, be either annulled or altered, much less can a divine covenant be changed, either in its promises or conditions. In the covenant with Abraham in reference to Christ, the inheritance, (that inheritance in which the gentiles share,) was suspended upon faith in the promise. The law, therefore, which was long subsequent, could not alter this covenant, or make the inheritance to depend upon works. Here everything is taught, first, the Abrahamic covenant had reference to Christ; second, the thing promised was that inheritance of which Christ is the author, and all nations (not the Jews only) the heirs; third, the condition on which a participation in this inheritance is suspended, is faith and not works.
—Charles Hodge, “Review of The Tecnobaptist: A Discourse, Wherein an Honest Baptist, by a Course of Argument to Which No Honest Baptist Can Object, Is Convinced That Infant Christians Are Proper Subjects Of Baptism by R. B. Mayes,” in The Book Reviews of Charles Hodge (repr. Bellingham, WA: Logos Bible Software, 2014)