Romans 4:1–12 focuses on the faith of Abraham, referenced by Paul to further his case about faith. God only declares people righteous based on their faith in Him. David, as well, describes those against whom God will not count their sin as ”blessed.” Paul insists that this blessing of being declared righteous by God is available to both the circumcised and the uncircumcised. After all, God declared Abraham righteous long before he was circumcised. In that way, he became the spiritual father of both the believing Gentiles and the believing Jews.
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“Romans 4:3” Bibleref.com
3 For what does the Scripture say? “Abraham believed God, and it was accounted to him for righteousness.”