Colossians 1:18 says that Jesus Christ is the Head of the Church. The Chief Shepherd (1 Pet 5:4) has delegated authority to a plurality of elders in each local congregation. No higher human leader exists in a church than that of an elder. Humanly speaking, the head of the church is not a senior-pastor or a deacon board, but a plurality of elders who shepherd the flock of God among them (1 Pet 5:2).
Office and Function of the Elders. 1 Peter 5:1-5, 1 Timothy 3:1-7, and Titus 1:6-9 are the definitive passages of the New Testament dealing with an elder's character, giftedness, and function. In addition, Acts 20:17-38 provides a narrative description of Paul's departure from the Ephesian elders where he exhorts them in their shepherding role of the flock. By examining these passages we learn about the office/function of elders. It is important to note the terms given for elders in the New Testament. 1 Peter 5:1 speaks of the presbyteros or an older man (note: this in no way means that a young man may not be an elder. Paul made this point clearly in his exhortation in 1 Timothy 4:13 where he viewed Timothy as the congregation's spiritual leader). In Acts 20:28 Paul calls them episkopos or a leader who watches over people. Finally, the verb poimaino meaning "to shepherd" is used in 1 Peter 5:2. These terms are used interchangeably in the New Testament, so an elder is an overseer who is a shepherd. This is the office of elder/pastor.
An elder is to "shepherd the flock of God", not be lording authority over them, but by being an example. A primary way to care for the flock is to protect them from wolves. Jesus Christ will one day judge whether or not the elder guarded and protected the flock under his care. False religions, false forms of Christianity, and false doctrine threatens to do harm to people. It is the biblical elder who understands the issues at stake and protects the flock from harmful influences.
Warning the flock of threats isn't the only type of teaching in which the elder engages. An elder also teaches the whole counsel of God (Acts 20:27), and as Paul made clear to Timothy, the elder also is to "preach the word in season and out of season (2 Tim 4:2). This is why one who holds to the office of elder must have the ability to teach (1 Tim 3:2).
Qualifications of Elders. 1 Timothy 3:1-7 and Titus 1:6-9 detail the qualifications for an elder. In addition to the character qualifications that must be evident in an elder, three other items are worth clarifying. First, an elder is a man. Second, a man must be able to teach. Finally, a man who is being considered for the office of elder must aspire to the work that they office requires. Shepherding a flock is time consuming, tiresome, and not always well-received. If a man does not aspire to this work, a man is not called to this ministry.
Appointment of Elders. Acts 6:1-6, Titus 1:5, and 1 Timothy 5:22 indicate that current church leaders are the ones who oversee the formal recognition of new leaders. Elder leadership of a local church is clear throughout the NT and so logically, elders possessing delegated authority from Christ are those in the local church who are responsible to populate the elder board. This process is not to be rushed (1 Tim 5:22) and will examine character, theology, ability to teach and defend the Faith, and willingness to do the work of shepherding the flock.