In the main body of Paul’s letter, he addresses a question: How do we know that the gospel Paul preaches is the true gospel? Paul answers by describing his personal experience of God’s grace, his reception of the gospel from God rather than from man, and the apostles in Jerusalem affirming the gospel he received from God. By looking at Paul’s story, we will see his defenses against the troublemakers’ attacks and how he illustrates the gospel of grace through his own life.