6 Just as Abraham “believed God, and it was accounted to him for righteousness.”
7 Therefore know that only those who are of faith are sons of Abraham.
8 And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel to Abraham beforehand, saying, “In you all the nations shall be blessed.”
9 So then those who are of faith are blessed with believing Abraham.
The answer to Paul’s question in verse 5 is so obviously “by faith” that he proceeds in verse 6 with that assumption.
believed God (v.6) — that God could and would fulfill His promise even though it was naturally impossible (Romans 4:19).
accounted (v.6) — reckoned, placed in his account in value as righteousness. Abraham’s faith wasn’t counted as a good work but as evidence that he cast off all dependence on works.
accounted to him (v.6) — not his originally.
for (v.6) = unto (Romans 10:10).
righteousness (v.6) — a condition of rightness the standard of which is God.
those who are of faith (v.7) — those who seek justification by faith
only those (v.7) — these and no others — not those of natural descent or who adhere to the law
preached the gospel (v.8) — anticipated, without revealing, the gospel
in you (v.8) — Abraham — it was through his descendants that the redeemer came, and he also began a line of those who are characterized by faith in God.
all nations (v.8) — Jews and Gentiles
It is true that all nations were to be blessed through Israel, Abraham’s multiplied seed (Genesis 22:17-18). It is also true that all nations were to be blessed through Christ, Abraham’s single Seed (Galatians 3:16). But the very first promise made to Abraham was that God would bless all nations through him, and the apostle quotes this promise in an argument that God justifies Gentiles through faith.
The original promise made to Abraham, then, holds out blessing to the world through Abraham himself. How has Abraham himself proved a blessing to all nations? There is only one answer: as God’s great example of FAITH. — Stam, page 150-151.
blessed (v.9) — salvation and all that results
with (v.9) — in fellowship with. Sharing Abraham’s faith, we also share what his faith received.
believing Abraham (v.9) — not because he was circumcised but because he believed.
The occasion for his argument is found in the fact that the Judaizers taught that the natural descendants of Abraham were his children, and thus accepted with God. All of which meant that only the circumcised could be saved. Thus, circumcision was a prerequisite of salvation. This teaching was based on a misapprehension of Genesis 12 and 17. They argued that no one could participate in the blessings of God’s covenant with Abraham, and so in the messianic salvation which was inseparably connected with it, unless he was circumcised. The mistake they made was in failing to distinguish between the purely Jewish and national covenant God made with Abraham, which had to do with the earthly ministry and destiny of the Chosen People as a channel which God would use in bringing salvation to the earth, and that salvation which came through a descendant of Abraham, the Messiah. Circumcision was God’s mark of separation upon the Jew, isolating him in the midst of the Gentile nations, in order that He might use the nation Israel for His own purposes. It had nothing to do with the acceptance of salvation by the Jew. Over against this contention, Paul argues that Abraham was justified by faith, not by circumcision. In Romans 4:9-10, he proves his case conclusively when he shows that Abraham was declared righteous before he was circumcised, which demonstrates that his circumcision had nothing to do with his acceptance of salvation. — Wuest, pages 88-89.