Paul stated that Abraham was justified by his faith instead of works. Faith comes from the heart; works from the flesh. His faith had led him to follow the commands of God. Works of the Law of Moses came many years after the justification of Abraham.
Even though the Jews were governed by the Law of Moses, they looked to Abraham as their father. Paul pointed out that Abraham’s faith was pleasing to God long before he was circumcised. He received the sign of circumcision as a seal of his righteousness, that he might be the father of all of those who believe. That included both Jews and Gentiles. This provided further evidence that uncircumcised Gentiles could be pleasing to God.
Paul concluded that since the promise was made to Abraham before the Law of Moses was given, one who tries to justify himself by the law instead of faith in God makes the promise become useless.
The apostle described Abraham’s faith as he continued to urge the Romans to have a like faith. Even though he and Sarah were well beyond the age of natural childbearing, God had said that he would be the father of many nations—not only the fleshly father, but also the spiritual father. The rewards of that promise are available to all of mankind through the death, burial and resurrection of Christ. Christians today, whether Jews or Gentiles are spiritual children of Abraham because of that promise.
Just as the high priest entered the most holy place in the temple annually and offered a lamb without blemish for the sins of the Jews under the Law of Moses, Jesus, as our High Priest entered the most holy place only once and offered Himself as a perfect Lamb for our sins.