The office of "bishop" apparently was non-existent in the first century. A number of sources demonstrate this datum to be the case including BDAG, but let us consult other works for now. Francis Beare writes concerning Phil. 1:1:
"The two [Greek] words translated bishops and deacons have been much debated. In the second century they became specialized in ecclesiastical usage; the bishop as the head of the local Christian community, the deacons as his assistants in whatever duties he might assign them."
Beare then adds: "Negatively, it may be said that the use of the plurals [in Phil. 1:1] rules out any possibility that the Philippian church is governed by a monarchical bishop."
After citing Polycarp and other sources, he concludes: "This passing reference [to EPISKOPOI and DIAKONOI in Phil. 1:1] does not provide us with any crumb of information about the status or function of EPISKOPOI and DIAKONOI at Philippi; and we are not entitled to read into them in this context the significance which belongs to them in later Catholic usage" (Francis Beare, Epistle to the Philippians, 1959, pp. 49-50).
So while the Primitive Congregation used such men to govern the ecclesia, it does not follow that these "offices" were hierarchically arranged or that these men were "leaders" of the Church.
Jesus Christ commanded: "Neither be called 'leaders,' [KAQHGHTAI] for your Leader [KAQHGHTHS] is one, the Christ [hO XRISTOS" (Mt. 23:10 NWT).
The term translated "Leader" can evidently mean either "leader, master, guide, teacher or professor." Certain scholars favor the sense "teachers" in this passage, but I think that "leader" is just as likely in view of Mt. 23:6-8.
The Geneva Bible of 1599 has: "Neither be ye called masters: for one is your Master, [even] Christ."
"Neither be ye called masters: for one is your master, [even] the Christ" (ASV).
"nor may ye be called directors, for one is your director -- the Christ" (YLT).
"Nor are you to be called ‘teacher,’ for you have one teacher, the Christ" (NET Bible).
The fact remains that the first century ecclesia had no human leaders: the closest the NT comes to using such language is Hb 13:7, 17. The head (KEFALH) of the congregation--the one who truly made the binding decisions under the guidance of holy spirit--was Christ (Col. 1:18). Those tending the first century ecclesia had to submit to their head and his God and Father (Eph. 1:17). Furthermore, it also seems that they were in subjection to the local congregation (ecclesia) that existed under apostolic governance. The EPISKOPOI and DIAKONOI were "individuals designated for special service within the Church and perhaps subject to the Church" (Gerald Hawthorne, Philippians, Word Series, page 8).
Heinrich Meyer likewise concludes: "We may add that placing of the officials after the church generally, which is not logically requisite, and the mere subjoining of them by SUN, are characteristic of the relation between the two [the overseers, the assistants and the flock], which had not yet undergone hierarchical dislocation" (Meyer, Philippians and Colossians, page 14).
To help list-members understand Meyer's comments concerning Phil 1:1, I post the Greek of that passage for you:
PAULOS KAI TIMOQEOS DOULOI XRISTOU IHSOU PASIN TOIS hAGIOIS EN XRISTWi IHSOU TOIS OUSIN EN FILIPPOIS SUN EPISKOPOIS KAI DIAKONOIS.