Paul addressed this letter to both Jewish and Gentile Christians in Rome​—the capital of the Roman Empire, the sixth world power in Bible history. Of the 14 letters that Paul wrote, this is the longest.​—Ro 1:7.

Romans is not the first letter that Paul wrote. Yet, in modern Bibles it precedes the others, which seems appropriate because it discusses a turning point in God’s dealings with his people. The book of Romans explains that the inspired Hebrew Scriptures had long foretold that the good news would also be proclaimed to non-Jews. (Ro 1:16) Paul, “an apostle to the nations,” discusses at length the equal standing that Jews and non-Jews enjoyed after accepting Jesus as the promised Messiah.​—Ro 11:13; 15:8-12.

The main theme of Paul’s letter to the Romans has to do with how righteousness, or a righteous standing before God, is obtained. That righteousness does not come as a result of ancestry or through works of the Mosaic Law. Rather, it is gained through faith in Jesus Christ and as a result of God’s undeserved kindness. (Ro 3:21-24; 4:4, 16) This theme is expressed at Ro 1:16, 17, where Paul quotes the prophet Habakkuk and states: “The righteous one will live by reason of faith.” In connection with this theme, God impartially holds out the possibility of salvation to everyone having faith, whether Jew or Gentile.​—Hab 2:4; Ro 2:10, 11.

In developing the theme of being declared righteous on the basis of faith, Paul uses the Greek term for “righteousness” over 30 times in the book of Romans​—far more often than this term is used in any other book of the Christian Greek Scriptures. Additionally, other words related to being “righteous” or “declared righteous” are frequently used in the book of Romans.

In this letter, Paul includes personal details that help his readers get to know him and love him as a genuine, devoted Christian. For example, he reveals his longing to see his fellow Christians in Rome (Ro 1:8-12), his personal struggle with sin in the flesh (Ro 7:7-25), and his pain and sorrow over the unbelief of his Jewish brothers (Ro 9:1-5; 10:1, 2; 11:13, 14, 25). He appeals to his readers “by the compassions of God.” (Ro 12:1) In the final chapters, he describes the extent of his preaching activities as well as his desire to preach to people who had not yet heard the good news. (Ro 15:20, 21) In the last chapter, he sends personal greetings to 26 Christians by name and to many others.