the longest and doctrinally most significant of St. Paul the Apostle's New Testament writings, probably composed at Corinth in about AD 57; it was addressed to the Christian Church at Rome, whose congregation Paul hoped to visit for the first time on his way to Spain. The letter has been intensely studied since early Christian times and was the basis of Martin Luther's teaching on justification by faith alone.

Paul's lengthy presentation is more a treatise than a letter but falls far short of a complete survey of his theology; there is no discussion, for example, of the Eucharist, the Resurrection, or eschatology.

Paul declares that God's righteousness has always been manifest in his dealings with men. Though the Apostle notes with pride the unique religious heritage of the Jewish people (the Covenant, the Law, the patriarchs, and Christ himself), he declares that righteousness no longer comes through observance of the Mosaic Law, not even for Jews, because God now manifests his righteousness through Christ, whose righteousness is the source of righteousness for all mankind. Paul, however, cautions his readers that righteousness is not a license to sin. The letter also contains several specific exhortations, such as to repay evil with good, to support and love one another, and to be obedient to civil rulers.