Several themes recur in Paul’s letters. Some of these are: the Gospel and doctrinal purity, Christian living, and relationships.
Paul was a preacher of the Gospel. He frequently reminded people to remember and stick to the Gospel he taught with directness and simplicity. There were a lot of false teachers who taught alternatives, often to draw followers and enrich themselves. In Paul’s teaching, everything depended on Christ and what He accomplished through His life, death and resurrection; nothing could be added or subtracted from it.
Of course, some tried to add or subtract. Some of the teachings Paul opposed were Judaizers, Gnostics, and legalism. Judaizers proposed that to be Christian, one must be Jewish first. This included conversion to Judaism, including circumcision, and observance of the law of Moses. According to the Gospel, everything needed was satisfied in Christ. The Gnostics came from the tradition of mystery religions, taught “secrets” and proposed a Christ who was resurrected as a spirit. Paul would have none of that either. The Gospel was plain and all significant events of Christ’s life for our salvation were publicly known, including his physical resurrection. Both of these groups touched to some degree on legalism. People wanted to establish rules to live by, either to control people or to aggrandize themselves or to suggest people had a part in their own salvation. Paul’s Gospel asserted that Christ is all, His sacrifice atoned for our sins and His power in us enables us to do good.
If Christianity wasn’t about following rules, how were we to live? Could we do whatever we wanted? Of course, it is silly to think that God would save us from our sins just so we could do whatever evil came to us. It was equally naïve to think we could, on our own, live up to any rule that is truly pure and perfect.
Instead, a Christian life should be typified by love, humility, gratitude, and obedience to God. We are to honor Christ our rescuer by imitating Him. This isn’t to win his favor, but to return the love He showed us and express gratitude for the mercy we did not deserve. Christ empowers us to live in a new way, knowing Him and doing good instead of sinning and becoming more estranged from God.
One of the most important ways we can show our love for God and be Christ-like is in our relationships with others. Paul wrote about all kinds of relationships: marriage, parent-child, employer-employee (in those days sometimes master-slave), and fellow in the church. We should treat others with the love, kindness and generosity that Christ shows to us, especially in the church.
The Pauline Letters appear in most Bibles generally from longest to shortest: Romans, First Corinthians, Second Corinthians, Galatians, Ephesians, Philippians, Colossians, First Thessalonians, Second Thessalonians, First Timothy, Second Timothy, Titus, and Philemon. First and Second Timothy, Titus and sometimes Philemon are called the Pastoral Letters because Timothy and Titus were young pastors.Google