To start with, there is a translation problem. The Greek word is presbyteros, an adjective meaning "older". But it doesn't really mean this. When we read that "the chief priests and the elders discussed how to put Jesus to death", it doesn't mean old men - it means the people in authority, the leaders of the synagogues.
Because it was a technical term, it was left untranslated when the Bible was put into Latin. And from Latin, the word crept into English, as priest, into French as prêtre, into German as Priester. And hence another problem, for there is only one word to describe both a priest in the Jewish temple (hieros in Greek, sacerdos in Latin), and the sort of person Paul and Barnabas "appointed in every church".
Paul himself, in his letters to the churches, never uses the word. But it appears in the Letters to Timothy and to Titus, and the Letter of James. "Is anyone among you sick? Let him call for the elders of the church, to pray over him and anoint him with oil." (Jas 5:14).
Elders were probably rather like their Jewish counterparts, the "rulers of synagogues". We have no idea whether in a given city there were one, or two, or twenty-five of them. At a period when the church was growing rapidly and haphazardly, there were apostles, prophets, teachers, miracle-workers, healers, helpers, administrators, people speaking in tongues (1 Cor 12:28). As time went on, the organization settled down, and became more like the church we know today.
Things changed after the original apostles died. One of the jobs of a "presbyter", or priest, had been "watching over" the flock to which one of the apostles had appointed him. In the Letter to Titus, we see this job of appointment being passed on to someone else (Tit 1:5). So a chain developed (a "hierarchy" if you like!) - there were three layers of service: those who watched over a wide area, those who watched over a congregation, and those who served in particular ministries.
In Greek, someone who watches over is episkopos, and because the word was used in a technical sense from the early days of the Church, it too was never translated, but became the English word bishop - evêque in French, Bischof in German. In New Testament times, the presbyteroi watched over the churches on behalf of the apostles - just as the apostles gathered in Jerusalem watched over the worldwide church on behalf of Jesus, "the shepherd and episkopos of our souls".
Jesus, our shepherd and guardian, chose disciples, and sent them out as apostles, shepherds and guardians like himself. The apostles appointed elders ("priests") to be shepherds ("pastors") and guardians ("bishops") of local churches. Later, the apostles chose people to carry on the work of appointing after they had died. It is to these people, people like Titus, to whom the term "bishop" eventually stuck.
From the days of the apostles onwards, the task of bishops was to "guard" the flock under their care, to ordain priests and to "watch over" them. In the Anglican Church, our bishops visit us frequently, know us individually (in theory at least, for it is they who have confirmed us!), and appoint pastors. The unbroken line of commissioning, going back from David Wotherspoon to Jesus himself, is something that guarantees the unity of Christ's body, the Church, and to us Anglicans, this "apostolic succession" is something very important - a witness that we stand in the tradition of the first followers of Jesus.
So what about deacons, curates, vicars, rectors, chaplains, deans, archdeacons, canons, suffragans, cardinals and popes? They'll have to wait for another article! But, like us, they all serve Christ, in ways God has chosen for us, as parts of Christ's body, doing his work and awaiting his Kingdom!
HD