Who is Paul? He is "a servant of Christ Jesus who has been called to be an apostle." (v1). He serves Christ. Christ sent him "to preach the Good News" (v2).
What is the Good News? The Good News is about Jesus Christ, Who was "a descendant of David" and was "proclaimed Son of God" (v4). By being a descendant of David, Jesus fulfilled the Old Testament prophecy that the Messiah ("The Anointed One of God") would come from the line of David.
Through His resurrection from the dead Jesus testifies to Himself as being the Son of God, in all His power (v4). To whom is the Good News to be preached (v5)? To "all pagan nations" (v5) and to everyone! This is good news!
Who is Paul? A persecutor of the Good News. But through the "grace" of God, he converted and received his "apostolic mission" (v5). He became a missionary of the Good News and as 'The Apostle to the Gentiles'.
Who are we? We are those who have heard the Good News. We are those who belong to Jesus Christ (v6). We are God's "beloved" and "called to be saints" (v7). We are those who are now entrusted to be witnesses of the Good News, where we are in a world that is immoral and hostile to the Good News. But we will rise up and fulfil this call of God in our life, as Paul did.
Lord, give us Your grace and peace to share the Good News with all.