Paul's letter to the Galatians is the first and most fundamental of all his letters because it establishes the Gospel of Grace. He expresses himself so strongly, because there is no room for compromise on the Gospel. We must stand firm and defend the true Gospel, for it is the power of God unto salvation (Romans 1:16). The first attack against the Gospel in Church history came from legalism, and it was the issue before the first Church Council in Acts 15. We show how Galatians 2:1-6 harmonises with Acts 15.