The Donatist controversy arose from the refusal of many to forgive priests—and others— who had apostatized during persecution. It ignores the simple fact is that the man who is a coward today may be a hero tomorrow. Anyone who has been in combat knows this. It also had to do with Punic rejection of Latin authority. Faith and culture became so intertwined that Augustine, who first sought to dialogue with the Donatists finally despaired and turned to the Roman governor to blunt the violent spirit of the locals. It was not among his most admirable decisions and proved conterproductive. Not only did the natives welcome the Vandals but centuries later they welcomed the Muslims.
As for the lack of warrant in the Scripture, that assumes that you know exactly what was in the mind of the authors of the letters. Clearly Peter does not resemble a renaissance pope nor Timothy a 15th century bishop. But I don’t HAVE to picture the pope this way either. The last three popes have discarded all the Constantinian imagery. The big difference in style between Billy Graham and John Paul II was that Billy wore a business suit. The real different, of course, is the authority that John Paul claimed. And this is our point of dispute. You reject the idea of a development of doctrine. I accept it, and I also accept the idea that authority takes on different styles throughout history. I can see the foreshadowing of the forms of the later priesthood in the New Testament record. Therefore you and I read “Hebrews”very different. I believe in the Apostolic succession, of a very human line of succession of authority. I believe in hierarchy.
The Lord Jesus commissioned certain men who in turn commissioned others down to this day. Christ, the High priest, has his acolytes—priests and deacons in the Temple (the Church). Their authority comes from him, not the congregation.
Regarding your tag, who are the "suffering souls" and where are they?