What does Romans 1:4 mean?

Paul, having just begun the greeting to his letter, is already sidetracked by proclaiming the gospel to his readers. He has said Jesus Christ is the focus of the long-ago promised gospel—the "good news"—from God.

Jesus, as a human being "according to the flesh" (Romans 1:3), was a direct descendant of King David. Now Paul adds that the resurrection of Jesus from death to life proves that He was more than just a man. That event, predicted by Jesus Himself (Matthew 28:6), established that He was in fact the Son of God. It was a declaration by the power of the Holy Spirit of God—"the Spirit of holiness"—that Jesus, as God's eternal Son, was in fact God. Who else could have raised Jesus from the dead but God's own powerful Spirit?

Already in verse 4, Paul has established the truth that Jesus was fully human and also fully God. As God's Son, Christ has reigned with God the Father forever. It is only right, then, that we should bow to Him as "Jesus Christ our Lord."