There are a number of passages in the New Testament that teach about the who and the why of local church leadership. The New Testament speaks of only two leadership offices for local New Testament churches, one of which has a couple of designations.
In the New Testament we find that the office of the elder is identified by two basic terms: (1) elder (presbyter, GR presbuteros), as a church leader (Acts ; 15:2, 2, 4) and, (2) overseer (bishop, GR episkopos), one who “watches over.” When it comes to the office of “Elder,” the term presbuteros stresses its dignity and the term episkopos its work. An important point to make is that the terms “elder” and “overseer” are used interchangeably in the New Testament, clearly indicating that both terms refer to the same office (cf. Acts 20:17, 28 and Titus 1:5, 7).
There are many passages of which only a few will be listed here, that teach us what the duties and responsibilities of an elder are (Acts 11:30; 15:2-6; 20:28; 1 Tim. 3:2; 5:17 Titus 1:7, 9; Heb. 13:17; James 5:14).
Only those who have met the qualifications given in the New Testament are to serve as elders. The qualifications of elders are found in 1 Tim. 3:17- and Titus 1:5-9. The New Testament also teaches that in any given local church, there should be a plurality of elders serving (Acts ; Phil. 1:1; Titus 1:5).
The word diakonos is the Greek word for deacon which means “servant.” Acts 6:1-6 appears to be the time in the very short history of the church where we find the origin of the office. While the elders are charged with the responsibility of praying and of teaching the assembly, the deacons are charged with the responsibility of handling the practical and material needs of the assembly.
As with the elders, only those who are qualified are to serve as deacons. The qualifications of deacons are spelled out for us in 1 Tim. 3:8-13.