Romans 1:1-6

¹ Paul, a slave of Messiah Jesus, called to be an apostle, that is set apart for the gospel of God, ² which was previously promised through his prophets in the holy scriptures, ³ concerning his son, who was of the seed of David according to the flesh, ⁴ who was declared 'Son of God' with power according to the Spirit of holiness, because of the resurrection of the dead, Jesus, the Messiah, our Lord, ⁵ through whom we received grace and apostleship to bring about the obedience of faith among all nations for the sake of his name, ⁶ among you also, who are called by Jesus the Messiah.

Interpretation:

Paul introduces himself here as a slave of Messiah Jesus, that is he is in the service of the true king, the king of Israel, the king of the world (see Psalm 2 for the background of the king of Israel being the king of the whole world). He is a slave of Jesus because he was appointed by king Jesus to be his herald, while he was traveling to Damascus (see Acts 9). Paul's life now (that is after his conversion on the Damascus road) is defined by his appointment to the gospel of God, which is the good news regarding the present reign of the king of Israel, whose name is Jesus.

This good news (gospel) was previously promised by the prophets in the Old Testament, and the good news specifically spoke of God's son. God's son (i.e., Jesus) was specifically in the lineage of David (for the importance of this see 2 Sam 7 and again Psalm 2), and declared 'Son of God' that is king of Israel by the Holy Spirit, who raised Jesus from the dead (Looking ahead a bit, there is a connection here in 1:4 with the words 'son', 'declared', and resurrection that Paul will pick up again in Romans 8:29). It is because of the resurrection and Jesus' Davidic lineage that Paul calls Jesus the Messiah (or King) and Lord (Notice these are titles used of Caesar, so Paul is offering a polemic against the rule of Caesar, while also showing that Jesus is the fulfillment of Israel's expectations).

Because Jesus is King and Lord, he gave to Paul the privilege of service in apostleship, which is designed to bring about the obedience of faith among all the nations for the sake of Jesus' reputation. The reasoning goes like this: Jesus is the King of all the world, thus all nations must come to obey him as the true King. So Paul's mission as an apostle is to announce Jesus' kingship over and against all other kings, so that rebels will obey the gospel, that is they will obey out of belief that Jesus is the king (Notice that the phrase 'obedience of faith' is contextual. The 'faith' is not generic faith, but faith in Jesus the king, which brings about obedience to Jesus' rule as king).

Paul in verse 6 now shows how his apostleship relates to the Romans. Because Paul is a herald of Jesus' reign, and is appointed to bring about the obedience of faith among the nations, and since the Roman Christians are called by Jesus the king, Paul's service to Jesus entails a responsibility over the Roman Christians. He is going to work out more obedience to Jesus among the Roman Christians.