1. Paul, a servant of Christ Jesus, called to be an apostle and set apart for the gospel of God—Apostle means one sent forth as a religious messenger and ambassador. That sounds like something I desire to be as well. I don't think I'll start using the title Apostle tho. :)
Gospel of God... I suspect this is the same gospel that Jesus preached. The good news of the kingdom of God. That Jesus should rule and we should not.
2. the gospel he promised beforehand through his prophets in the Holy ScripturesWhat good news promised by the prophets is Paul referring to? Well we know the Jews were waiting for a messiah. An anointed king to rescue them from other powers that ruled over them. And that is exactly what Jesus came to be. Not to set up an earthly kingdom, but to free us so we can be ruled by His will.
3. regarding his Son, who as to his human nature was a descendant of David, 4 and who through the Spirit of holiness was declared with power to be the Son of God by his resurrection from the dead: Jesus Christ our Lord.
By being a descendant of David Jesus met a requirements to be an earthly Jewish king. By being the Son of God Jesus meets the requirements to be our spiritual King.
Jesus Christ our Lord... to me this is another way of saying Jesus you are King... reign in my life now and into eternity.
5. Through him and for his name's sake, we received grace and apostleship to call people from among all the Gentiles to the obedience that comes from faith. 6 And you also are among those who are called to belong to Jesus Christ.
This brings me back to the term apostle. Here Paul implies he and others are apostles. How many apostles are there? I thought there were only 12 or 13 if you count Paul. Then I find Ephesians 4:11-13 (NIV).
It was he who gave some to be apostles, some to be prophets, some to be evangelists, and some to be pastors and teachers, to prepare God's people for works of service, so that the body of Christ may be built up until we all reach unity in the faith and in the knowledge of the Son of God and become mature, attaining to the whole measure of the fullness of Christ.
Until we all reach unity... OK, there is likely still a place for the role of apostle... to be sent out as ambassadors of the good news of God.