It’s complicated. History is never neat and tidy as we would like it to be. I don’t know Greek, but have researched the relevant terms in reference works:
- **έπίσκοπος **= bishop / overseer
- **πρεσβύτερος **= elder / presbyter / ancient / priest
- **διάκονος **= deacon / servant
So “bishop” and “elder” are not the same word, however, they are sometimes used interchangeably in the N.T. and early Christian writings (the CA tract explains why). The word “elder” may have one of a number of different meanings depending on the passage. So it’s not like you can just point to the Greek words and say, “See! There the titles are, therefore the
hierarchia ordinis is in the Bible!” You have to rely on context.
Be aware that there is a Greek word for “priest” (ἱερεύς), which usually refers to a priest of the Old Law (sometimes it refers to pagan priests, sometimes to the priesthood of the faithful, etc.). I don’t have it in front of me, but the Roman Catechism says in the section on Holy Orders that the term “elder” was chosen because of the wisdom (and I think age) required for the office, or something to that effect. The Church Fathers, however, do apply the term ἱερεύς to a priest of the New Law.
There is more; this is just to get you started. In addition to the CA tract, I’d recommend the Catholic Encyclopedia articles “Priesthood,” “Bishop,” and “Hierarchy of the Early Church.”
