In Chapter 3 of St. Paulโs letter to the Romans he declares that God has set forth Christ as a satisfaction for manโs sin and that redemption is obtained by faith in โHis blood,โ or His payment for sin at Calvary, entirely apart from works, religious or otherwise (Rom. 3:21-26).
But in this same passage he states that this โremissionโ concerns the โsins that are pastโ (Rom. 3:25). What does he mean by this? Some have taught from this verse that when a sinner turns to God for salvation all his sins are forgiven up to that time and now that he is saved he is henceforth responsible for himself. But this would mean that God saves men by His grace only to turn them over again to their own weak and sinful natures. If this were the case, the converted sinner would be lost again the same day, for what Christian believer is wholly free from sin?
Paul rather looks back here at past ages and declares that we now know and proclaim that men like Abel, Noah and Abraham, and also like Moses, David and Daniel (who lived under the Law) were actually saved by the redemption wrought by Christ, although Christโs death was still future in their day. In other words, Christ died, not only for the sins which we have committed, but also for the โsins which are past.โ The believers of past ages simply believed what God told them then, and God counted them righteous (Gen. 15:6) on the basis of Christโs coming payment for sin.
We have the same truth set forth in Hebrews 9:15, where we are told that Christโs death availed also โfor the redemption of the transgressions that were under the first covenant,โ i.e., the Law.
How blessed we are to live at a time when Godโs plan of salvation has been fully revealed, and that we can now look to the Lord Jesus Christ and exclaim with Paul:
โHe loved me, and gave Himself for me!โ (Gal. 2:20). source