John Calvin Explains the Origin of Bishops
At the time of the Protestant Reformation, Martin Luther, John Calvin, and other leaders were attempting to reform the abuses of the Roman Catholic Church. Many rules and traditions had been added to the church since the time of the New Testament and the Protestant Reformers wanted to correct those abuses by returning to the time of the early church. One of the traditions that developed over time was the office of bishop. The Roman Catholic Church claimed that the office of bishop as practiced in the Middle Ages was necessary and ordained by God. Furthermore, the Catholic Church claimed that the Apostle Peter was the first bishop of Rome and therefore, Peter was the first pope.
In his book "The Institutes of the Christian Religion", John Calvin explained that bishops in the early church did not have the same power and status as that held by Roman Catholic bishops in the Middle Ages. The office of bishop was originally established for the sake of settling arguments and promoting efficient administration. The bishop was originally more like an administrator and facilitator than an authoritative ruler. Along with church elders, he was a leader among equals, not an authority who could command them all what to do.
A lot more could be said about the origin and development of the office of bishop and the original meaning of the words commonly translated as "bishop" or "elder". However, I want to share the short passage below written by John Calvin because he explains well the role and function of bishops in the early church era after the time of the apostles. The section below is from Calvin's Institutes, Book 4, Chapter 4, Section 2 from the English version of the Institutes translated from Latin by Ford Lewis Battles. A Thai translation is available here.
The position of the bishop
‘All those to whom the office of teaching was enjoined they called “‘presbyters.” In each city these chose one of their number to whom they specially gave the title “bishop” in order that dissensions might not arise (as commonly happens) from equality of rank. Still, the bishop was not so much higher in honor and dignity as to have lordship over his colleagues. But the same functions that the consul has in the senate—to report on business, to request opinions, to preside over others in counseling, admonishing, and exhorting, to govern the whole action by his authority, and to carry out what was decreed by common decision—the bishop carried out in the assembly of presbyters.
And the ancients themselves admit that this was introduced by human agreement to meet the need of the times. “Thus Jerome, commenting on the letter to Titus, says: “Bishop and presbyter are one and the same. And before, by the devil’s prompting, dissensions arose in religion and it was said among the people, ‘I am of Paul, I of Cephas’ {I Cor. 1:12; cf. ch. 3:4], churches were governed by the common counsel of presbyters.’’ “Afterward, to remove seeds of dissensions, all oversight was committed to one person. Just as the presbyters, therefore, know that they are, according to the custom of the church, subject to him who presides, so the bishops recognize that they are superior to the presbyters more according to the custom of the church than by the Lord’s actual arrangement, and that they ought to govern the church in co-operation with them. Jerome, however, tells us in another place what an ancient arrangement it was. For he says that at Alexandria from the time of the Evangelist Mark to that of Heraclas and Dionysius, the presbyters always elected one of their number and set him in a higher rank, calling him "bishop."
Each city, then, had a college of presbyters, who were pastors and teachers. For all exercised among the people the office of teaching, exhorting, and correcting, which Paul enjoins on bishops [Titus 1:9]; and, to leave successors after them, they labored hard to teach the younger men who had enlisted in the sacred army.
A certain area was assigned to each city from which its presbyters were drawn, and it was thought of as belonging to the body of that church. Each college was under one bishop for the preservation of its organization and peace. While he surpassed the others in dignity, he was subject to the assembly of his brethren. But if the field under his episcopate was too large for him to be able to fulfill everywhere all the duties of bishop, presbyters were assigned to certain places in the field, and carried on his duties in lesser matters. These they called "country bishops" because they represented the bishop throughout the province.