As Paul quoted David the Psalmist to describe the blessedness of God’s forgiveness without our works, he returns to his example of Abraham to prove that this blessedness, righteousness without works, is available to all, not just those who counted themselves as Abraham’s descendants.God had given the people of Israel, beginning with Abraham, the sign of circumcision, without which every man was cut off from being an Israelite, one of God’s chosen and favored people. And the Jews of Paul’s day were particularly strict about this, refusing to have anything to do with anyone who was not circumcised. When God sent Peter to preach to Cornelius’ household, and the Holy Spirit of God came upon this Roman and his people, it sent shock waves throughout the Jewish Christian community.
So Paul, in his exposition of the Gospel of Faith written to the Christians in Rome, takes a good deal of trouble to prove that acceptance by God through faith is available to all, Gentiles as well as Jews. And here in Romans 4, he lays out the historical fact that God counted Abraham righteous by his faith, BEFORE Abraham was circumcised. Circumcision was only a sign that God gave Abraham after He had already accepted him because of his faith. In other words, righteousness by faith pre-dated acceptance by circumcision. Thus, Abraham is the father of all who are righteous by faith, including both the Jews who failed to keep the law perfectly and the Gentiles who never had the law.
Long ago, God had promised Abraham that his children would be as many as the sand of the sea, and as the stars in the heavens. Through the shed blood of Jesus Christ, the spiritual children of Abraham now include countless souls who, like Abraham, are counted righteous by God through faith.