Abraham Counted Righteous before Circumcision
Paul asks what Abraham discovered. Genesis 15:6 gives the decisive answer: Abraham believed God, and it was counted to him for righteousness. Paul then brings David alongside Abraham by quoting Psalm 32:1–2 about the blessedness of forgiven sin and righteousness counted apart from works.
The chronology matters. Genesis 15 precedes the circumcision command of Genesis 17. Paul therefore argues that Abraham was counted righteous while uncircumcised, making him father of believing Gentiles as well as circumcised people who walk in the faith Abraham had before receiving the sign.
Aha: Paul’s argument depends on reading Genesis carefully in sequence. Theology comes out of the story’s order: promise and faith, then covenant sign.