The doctrine of justification by faith alone was not invented by the New Testament authors. The Apostle Paul demonstrated that both Abraham, the father of the nation of Israel, and David, Israel’s most renown king, were justified by faith alone (Romans 4:1-8).
The Apostle then goes on to illustrate that even circumcision, the covenant sign of Israel, was given to confirm the doctrine of justification by faith alone. Circumcision was not an action done to earn favor with God, but a proper display and response to the favor God gives as a gracious gift received by faith alone.
The Apostle said, “For we say that faith was counted to Abraham as righteousness. How then was it counted to him? Was it before or after he had been circumcised? It was not after, but before he was circumcised.” (Romans 4:9–10, see also Genesis 15 and 17) Circumcision was not the basis of Abraham’s righteousness before God, circumcision confirmed the gift.
God’s gracious character has not changed between the Old and New Testaments. The blessed person of the Old Testament is really the same type of person in the New Testament, because both come before the same God. The only difference between them is their place in time relative to the unfolding of God’s plan of salvation on earth. The believers of the Old Testament trusted in the shadow and symbolically displayed the grace of God through the covenant sign of circumcision. Believers today now see the body of that shadow and symbolically display the grace of God through the covenant sign of baptism. Both covenant signs – though different relative to the stage of God’s plan of salvation in which they were instituted – point to the same gracious gift of God.
The Apostle goes on to say, “Abraham received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. The purpose was to make him the father of all who believe without being circumcised, so that righteousness would be counted to them as well, and to make him the father of the circumcised who are not merely circumcised but who also walk in the footsteps of the faith that our father Abraham had before he was circumcised.” If Abraham placed his faith in God while only having a shadow, how much more should we who have the body of that shadow – Jesus Christ crucified and risen from the dead – place our faith in the free gift of God? (Romans 4:11–12)