Development of the Clergy
The Apostolic Direction
The ecclesias, as the apostles left them, were autonomous and self-governing. There were bishops and traveling overseers selected for their duties by the apostles, but there was no provision for the continuation of a hierarchy. Bishops (overseers), elders and deacons appear in the apostolic church, and since qualifications are given for the guidance of the ecclesias in choosing their elders, it must be assumed that they would be assigned to their positions by the will of the membership.
In the New Testament the words bishop and elder seem to be used interchangeably, as in The Epistle to Titus, 1:5-7. “Ordain elders in every city, as I appointed thee … for a bishop must be blameless …” I Tim. 3:1-13 qualifies both bishops and deacons, emphasizing that those who serve the ecclesia must be responsible and dedicated disciples.
The Second Century
At the beginning of the second century the same order prevailed. Presbyters (elders) were elected in some manner by their respective ecclesias. The larger ecclesias would have a bishop who was also one of the presbyters. There were also deacons (and deaconesses) who took care of various arrangements, and looked after the welfare of the individual members. Each of the ecclesias was independent, though they formed a collective body. Letters of exhortation, sometimes containing reproof, were sent between the ecclesias, but one did not exercise authority over another.
Article here.
