In my Introductory Post to this series, we presumed to agree that all who have ever been saved, are saved, and ever will be saved, are so because of the life, death, and resurrection of the Lord Jesus Christ, and through faith in Him. But the question was posed, if this is true, how was the redeeming work of Christ administered to the saints in the Old Testament—before Christ had come to do His redeeming work?
The Westminster Confession of Faith expresses well the traditional Reformed Covenant Theological answer to this question. After introducing the “Covenant of Grace” in contrast to that of works, “wherein [God] freely offers unto sinners life and salvation by Jesus Christ,” we read,
This covenant was differently administered in the time of the law, and in the time of the Gospel: under the law it was administered by promises, prophecies, sacrifices, circumcision, the paschal lamb, and other types and ordinances delivered to the people of the Jews, all foresignifying Christ to come; which were, for that time, sufficient and efficacious, through the operation of the Spirit, to instruct and build up the elect in faith in the promised Messiah, by whom they had full remission of sins, and eternal salvation; and is called the Old Testament. (Ch. 7.5)
In short, the answer given was that the redeeming work of Christ was administered in real time to the saints of old by the Old Covenant itself, through the covenant promises of (1) the Seed, (2) the Land, (3) through Circumcision, (4) the Sacrifices, (5) the Law itself, and (6) through Prophecy. Not only were these covenant promises and sacraments the means of administering Christ, they were by His Spirit “sufficient and efficacious” to that end.