Romans 1:1-7; Psalm 97:1-4; Luke 11:29-32
The order of Pauls lettters in the Bible are not chronological - they are simply ordered by length - and the letter tot he Romans is comfortably the longest.
At the time it was written - well, it still is - Rome was a cosmopolitan city, with Jews, Gentiles and a migrant population from everywhere - such was the spread of the Roman empire. There were consequently difficulties, and Paul had to face up to them. He himself was Jewish, but also a Roman citizen, and the new church he was building had to welcome both, despite their differences.
He begins his letter to the Romans with an expansive, warm welcome, explaining who the good news is about. Jesus was a son of David (clearly, Jewish), but also Son of God - which is much more important than his human family. The term 'Good News' was common to the roman empire - every time an emperor won a battle or had a son born to him, the Good News was spread rapidly throughout the empire.
This Good News, is the best of possible good news - God sent his son into the world to be the means of his salvific work.