What did Paul and Barnabas go to Jerusalem to prove to the leadership there?
They went to prove that nothing can be added to the relationship between Christ and the believer except faith, and faith alone in Paul’s Gospel. Their point was that salvation rests entirely on faith, not additional requirements, and they communicated it carefully point by point, line upon line.
Les explains that Paul and Barnabas came from Antioch to Jerusalem to prove to the Jerusalem leadership that you cannot add anything to the relationship between Christ and the believer except faith, and faith alone in Paul’s Gospel. They did not just flippantly say what they believed; they sat down and looked at it point by point, line upon line, because the revelations that came through the Apostle Paul were so above and beyond Judaism that the people needed time to understand where he was coming from. Les also connects this to Romans 1:16, where Paul says he is not ashamed of the Gospel of Jesus Christ, for it is the power of God unto salvation, and notes that salvation includes justification, sanctification, forgiveness, redemption, baptism into the Body of Christ, and the indwelling Holy Spirit.