Apostolic authority is a subject often assumed, but rarely discussed in Bible studies. Why do we care so much what a renegade Jew who traveled Eastern Europe wrote on the matter of Christianity. What gives him the right to dictate for us the doctrines, teaching, and even the very Gospel which cannot be contradicted by any man, nor even an angel from heaven (Gal. 1:8)?
Paul builds his defense first drawing upon the source of his knowledge. Paul was clear in Galatians 1:11-12 that he received this gospel from no man, but from Christ himself. I asked a class, what would have been different if Saul had believed upon hearing Steven's sermon in Acts 7? The answer: he would not have met the qualifications as an Apostle. But when God was pleased to reveal His Son to Paul (1:15), then he received Christ by special revelation from the resurrected Christ.
What Paul so adamantly defends, no other teacher, pastor, missionary, or theologian in the church today can assert. Paul's authority is apostolic. As one who received the gospel direct from Christ, and learned direct from Christ, his office in the church is uniquely authoritative. There were 12 others with the same station in the early church. Some of whom wrote instruction to the early church, along with Paul, that we still have today. And, because of the authority we know to be true in Apostles, this collection of Apostolic writing is counted infallible, as the words of the prophets who came before.
No other Christian thinker, teacher, theologian, clergy, or otherwise has written anything which the evangelical community would consider God-breathed scripture. As we study Paul's authority in the first two chapters of Galatians, then, we study the basis for Biblical authority. This is the reason that we can debate Luther, but not Paul... or that we can dispute Augustine's writings, but not Peter's... or this very blog, for instance, but not the writings of James, John, and the other New Testament writers.
So, knowing the authority with which Paul's words come, how then should we hold these teachings in our own lives? I rarely get more animated in an argument than when someone opposes the clear teaching of scripture. I tolerate direct disagreement from my students gladly, but nothing angers me more deeply than when they refuse to yield to the authoritative, Apostolic writing of Paul, Peter, James, John, or any of those reputed to be pillars.