Paul writes what Beker calls a “dialogue theology” (J. Christiaan Beker, Paul, the Apostle). What he means by this is that in every letter Paul’s audience defines how he will discuss the shape of Christianity for that particular audience given their particular interests, concerns, and dilemmas. So in a letter to a Jewish audience, issues which concern them will be discussed and will shape what he means by Christianity (given those issues), and in a letter to Gentiles, their interests and concerns will shape what he means given these concerns. In doing so Paul develops a universal Christianity; that is, a Christian faith for all people. What then forms the core of Paul’s understanding of the gospel? If you read Romans you might think it is the law, and for them and Paul, the law is important because they were Jews before they became Christian. But for the Gentiles, the laws, especially of circumcision and of purity and foods, were irrelevant. For Paul, the core of our faith was that we are all under indictment of our sins, but that by faith in God’s grace in the death and resurrection of his son Jesus we are saved. So whether Paul is upset with the Galatians for trying to become Jews, or he is pointing out to the Roman congregation of Jews the relation of Judaism to Christianity, or as in 1 Corinthians he is answering a series of written and oral questions for a congregation in the busiest port city on the Mediterranean, the gospel is always the same: the saving grace of God’s generous act in the death and resurrection of Jesus. We receive this salvation through no works of our own but through faith. Another key to reading Paul is to know which letters he wrote because a number of letters bearing the name Paul as the author were written by someone other than Paul. The letters normally considered authentic are Romans, 1 & 2 Corinthians, Galatians, Philippians, and 1 Thessalonians.