Of all the men on the earth, the Lord chose Abraham to be the forefather of His people. From the very beginning of his call, the Lord was requiring of Abraham faith: in Gen. 13:1, the initial command is to go “to the land that I will show you.” This means that God had not revealed this land to Abraham; in other words, he did not know where to go, only that he was to go. And it is this same faith upon which the Abrahamic Covenant is built: “Abraham believed the LORD, and He credited to him as righteousness” (Gen. 15:6). The Lord first made a promise to Abraham, which was to make his offspring number like the stars, to possess the land of Canaan, and to be a blessing to all nations. And this is the promise which Abraham believed, and this belief was credited to him as righteousness.
Thus we see another proof that men may only be declared righteous by God through faith, and that this faith is believing, or trusting, that the Lord will keep His promises. For New-Testament Christians, the promises of God are salvation by the blood of Christ, sanctification worked out by the Holy Spirit, glorification on the Day of the Lord, and, throughout the entire expanse of our temporal life, fellowship with the Triune God. Like that of Abraham, ours is founded upon faith, and from that faith springs outward evidences.
For Abraham, this sign of faithfulness was circumcision. The Lord said, “You must circumcise the flesh of your foreskin to serve as a sign of the covenant between Me and you” (Gen. 17:11). We know, therefore, that this act did not obtain right-standing with God for him, for it came after the Lord had already accepted Abraham and declared him to be righteous. Rather, circumcision was to be a signal, displaying that these people – Abraham and his folk – were believers in the promises of God, that they trusted the Lord. This work did not grant them righteousness: rather, this work was a proof that they had covenantally been declared righteous by the Lord. Notice also that God said, “If any male is not circumcised in the flesh of his foreskin, that man will be cut off from his people; he had broken My covenant” (Gen. 17:14). That is to say, if any man does not exhibit the outward proofs, then it is clear that he has no faith and that he has no place with God’s people. It is a stern word, but a necessary one.
This is the way in which our own covenant works. We trust that God, who is good, will keep His promise that whoever clings to the atoning sacrifice of Jesus shall be saved. From this faith and as a testimony of the good work which God has begun in our hearts – and which He is sure to finish – springs forth a life of walking in the good works which God prepared for us from the beginning, all that we might lift up His grace and His mercy and His own infinite glory.