Jesus, and His early followers were predominantly Jewish, therefore, their authority came from what is called the Old Testament. God had revealed Himself to His special people giving them His instructions on life and practice in His Kingdom.
Jesus’ coming on the scene was a game changer. One was to worship the Old Testament God who chose a new means of self-revelation, Jesus of Nazareth. Much can and will be said eventually about the relationship between the Father and the Son, but now just know that Jesus claimed to be and ended up proving He was/is God. This meant followers of God no longer were to exclusively follow the Old Testament but now they were to follow what Jesus said and what He taught. Nothing was written down to document what He said and did until after His death and resurrection.
So the question then is, where did followers of Jesus get their theological authority after Jesus ascended into heaven? Still very little was written down so they needed to figure out how to make decisions of religion without their Messiah. I am asserting that the followers of Jesus talked to and wrote letters to the Disciples in order to get their theological questions answered. So I believe the next step in the ‘theological authority’ concept is THE APOSTLES.
Jesus taught, lived with, and trained these 12 men while He was ministering in Israel. He was training them to take the mantle of authority after His departure. Therefore I believe the earliest of Christians asked the Apostles to assist them in their inquiries. The Apostles were special people only because Jesus had chosen them and given them at Pentecost the Holy Spirit to empower them to do His work and fulfill His commission. Some of them were also given the task of writing down not only accounts of the life and ministry of Jesus, but words of wisdom and authority to churches on how to live a life pleasing to the Father. Early Christianity saw the special role the Apostles were given, therefore they asked the Apostles for clarity in the pursuit of serving their Messiah.
Simply put: the first theological authority was Jesus, then when he was gone the next authority was the Apostles. The tricky issue will come when the last of the Apostles die (John around AD 100) and NOW WHAT DO THE CHRISTIANS TO GET THEIR THEOLOGY QUESTIONS ANSWER. I’ll take up the next authority next time.