Romans 4 quotes Genesis 15:6 and builds a major argument around it: Abraham was counted righteous through faith before circumcision and before the Sinai law. Paul also quotes the stars/seed promise and emphasizes that Abraham trusted God when the fulfillment looked humanly impossible. Galatians 3 again quotes Genesis 15:6 to explain the family of faith. James 2 quotes the same verse while showing that Abraham’s later obedience demonstrated the living character of the faith he professed.

These New Testament writers are not importing a foreign idea into Genesis; they are explicitly interpreting Genesis 15. At the same time, Romans and James should not be flattened into opponents. Paul argues against earning right standing by works; James argues against a claimed faith that produces no faithful action. Both appeal to Abraham, but for complementary questions.

The integrated story is: promise of descendants → human impossibility → God’s word → Abraham believes → righteousness counted → Romans, Galatians, and James explicitly return to this verse → the Abraham story becomes foundational to the New Testament explanation of faith and righteousness. Few passages better demonstrate the Old Testament being opened by the New.