The Gospel Promised, the Son from David
Paul begins Romans by saying the gospel was promised beforehand in the holy Scriptures. It concerns God’s Son: descended from David according to the flesh and declared Son of God in power according to the Spirit of holiness by resurrection from the dead. The opening therefore refuses to treat Jesus as a detached new idea; the gospel arrives as the fulfillment of a long biblical story.
Where this fits in the story: the Davidic covenant promised a royal line, the prophets kept alive the expectation of God’s saving reign, and the resurrection identifies the crucified Jesus as the living messianic Lord. Paul’s own apostleship exists to bring about the obedience of faith among the nations for Jesus’ name.