John believe that John brought the doctrine of clean living, but he was like Luther, who brought us living by faith, just a reformer. The Christain church could not agree on anything, WHO WAS RIGHT? I believed that God sent a man who had 'THUS SAITH LORD and brought a message to get the Christain church ready for the Rapture.
The leaders were decided by the good lord Himself through godly men who were sent to guide His church.
You have correct doctrines scattered throughout the church and he pointed by Gods's grace what the correct doctrine is. That in my opinion is HEB.13.8. Jesus Christ yesterday, today, and tommorow.