What does Romans 1:3 mean?
Paul is so eager to begin teaching about the gospel of Jesus Christ that he seems unable to even wait to finish the opening greeting to his letter. He has written that the gospel is something God promised long ago through His prophets in the Old Testament Scriptures. Now he continues that the gospel is about Jesus Christ.Jesus, as a human being, was a direct descendant of King David. That will become important to Paul's case that Jesus is the Messiah because of the prophetic Old Testament promises that one of David's descendants would sit on the throne of Israel forever (2 Samuel 7:12–16). In the following verse, Paul will show that Jesus was more than just a fully-human man.
Gospels such as Luke and Matthew also provide a genealogy of Jesus to demonstrate that He comes from this Davidic line. The theme of proving that Jesus is the Messiah, and the One promised by the Jewish Scriptures, is also found in books such as Hebrews.