Jesus, King of Heaven and Earth
The theme of Romans, though it varies at points, is that God’s righteousness is coming upon the creation through Christ. The foundational Gospel for Paul is the Kingship of Jesus. Paul understood Jesus as the rightful King in the line of David to inherit the throne of Israel.
Jesus received majesty, honor, and glory from the Father. These are kingly terms, referring to the extent of his sovereignty. Even before Jesus went to the cross, on the Mount of Transfiguration, the disciples got a glimpse of the kind of authority Jesus was destined for, even if they didn’t fully understand it at the time.
Grace for Paul is not just the forgiveness of sins, but the transformation from sinner to saint and restoration to right standing with God and the Kingdom of God. Paul believes part of grace is that his apostleship–and by extension, the church–is to bring about the obedience or righteousness of Christians. So there is a righteousness that is produced through the church that is expected as a product of grace.
The logic is that because Jesus is King, grace has been poured out on us so that we become obedient to God and go out to the nations so that they become obedient.