The last of Jesus’ apostles, John, died around the year AD 100. According to many legends and much reliable materials (Eusebius of Caesarea’s Ecclesiastical History) we know most of Jesus’ apostles (if not all but John) died martyrs. John’ brother James, for instance, was beheaded under the reign of Herod Agrippa. The death is recorded for us in Acts 12. Tradition tells us Peter was crucified upside down. Paul the Apostle was beheaded according to the right of a Roman citizen to have certain rights, including NOT crucifixion.
As these men were spreading the Gospel, many of them (along with some associates) were writing down the words of God through inspiration of the Holy Spirit. They were literally writing down the very words of God. These words (later called the New Testament) would become the next step on our journey of asking about theological authority.
While the apostles were living they were the instrument of God’s authority. But after John dies the question come up, ‘from where did the Christians get their authority’. I believe the Holy Scriptures fulfills this need.
The Bible is God breathed (2 Timothy 3:16) and therefore IS the very words of God. So once the followers of Jesus asked questions about theology they consulted the Scriptures. Almost at the same time, however, some decided the answers should come from groups of knowledgeable believers that could reason through the difficulties. They periodically called together groups of leaders into a council to discuss the major issues and heresies. Some of the Christians (later to be called the Orthodox Church) claim their authority comes from 2 places: the scriptures and the councils.
So in our study of theological authority the list so far is like this: the Old Testament, then Jesus, then the Apostles, then the Scriptures.