When Christ established His church it was His desire to see it continually tended to by mature spiritual leaders. In it's infant stage the church was directed by Christ's chosen Apostles. As men inspired by the Holy Spirit the Apostles led the church and delivered all (Jude 3) of God's instructions for how to live and worship. Part of those instructions were that each congregation would have its own group of shepherds. These men are required to meet a very specific set of qualifications in order to serve in such an important capacity (1 Timothy 3:1ff; Titus 1:5ff). Where the Apostles had the authority to establish doctrine, the eldership only has the authority to uphold biblical doctrine. Shepherds insure that the sheep are continuously fed a well-balanced spiritual diet and are always on the lookout for wolves that might do harm to the well-being of the congregation (Matthew 7:15; Acts 20:29).
The New Testament further lists a special group of men who must meet specific qualifications - deacons(1 Timothy 3:8ff) . While deacons carry no authority, the importance of their work should never be minimized. Deacons are servants that labor diligently to accomplish a multitude of tasks which, in turn, allows the elders to devote their time to weightier matters in the kingdom, such as visiting those sick and in the hospital, those struggling with deep spiritual issues, those battling the desire to go back to the world, teaching, preaching, etc...
While many in the religious world refer to a preacher as The Pastor the Scriptures offer a different view. A pastor is simply another term for an elder, overseer, or shepherd. Various names are used in the New Testament simply to show different aspects of the work of an elder. Interestingly, the New Testament calls for a plurality of men to serve in an eldership thus eliminating any one man being The Pastor or any other title that would designate someone as the head of a congregation. So, what authority does the preacher have? The preacher(s) actually works and labors under the oversight of the local eldership. His solemn charge is to preach the word (2 Tim 4:2). No person or group of people can ever authoritatively demand that he not declare the whole counsel of God. The preacher must ever be aware that he is God's mouthpiece to the church and by accepting such a great challenge must always remember his judgment will be more severe (Jas. 3:1). Otherwise, the preacher carries no authority.