The Role of Pastors
If we look at Ephesians 5:18 and the verses which follow we discover that singing is a vital part of the spiritual life as a consequence of being filled with the Spirit. NASB "And do not get drunk with wine, for that is dissipation, but be filled with the Spirit,  speaking to one another in psalms and hymns and spiritual songs, singing and making melody with your heart to the Lord." So we are told to be filled with the Spirit and after that there is a series of participles that describe certain consequences of being filled with the Spirit. So singing the great hymns of the faith, especially the ones filled with doctrinal content, are part of the spiritual life and is not something to be considered just some sort of addition that is tacked on at the beginning of church, or something that is what people just do traditionally. It is a vital part of Christian worship.
Paul was facing a particular problem with the congregation at Corinth, one that is not uncommon today, and that is the problem of authority. They were rejecting his authority and were in rebellion against him and everything that he taught, and that was one of the reasons he had to write this epistle which is such a strong message of correction. But the issue for every pastor is authority and the issue in many congregations for pastors is authority because congregations usually don't understand that the pastor is not the employee of the local congregation.
1 Corinthians 4:1 NASB "Let a man regard us in this manner, as servants of Christ and stewards of the mysteries of God." This begins with the particle HOUTOS [o(utwj] which actually means "in such a way" or "in such a manner," and it points to what is about to be said. This is the same word that we find in John 3:16 where we find that "God so loved." The word "so" is the same word as in our verse, HOUTOS, and it means, "God loved in such a manner/such a way." And then is describes the way or the manner in which God loved us: by sending His Son to die on the cross as a substitute for our sins. So each person is supposed to think a certain way about pastors, and this would include missionaries and evangelists, anyone who is in a professional Christian ministry.
A fourth system of government, not mentioned last time, is, for lack of a better term, pastor-rule. In these congregations the pastor makes all the decisions and he appoints certain men certain jobs.
The responsibility of the pastor-teacher
1) The pastor-teacher's responsibility is to lead the congregation and he does so primarily through the teaching of doctrine, through the Word of God.
2) The pastor-teacher sets certain policies, goals, and the agenda for the congregation. The deacons' responsibility is to carry out those policies and to implement them. But they are also accountable to the congregation, not in any extreme way, but remember, nobody is not accountable, nobody is autonomous, nobody is outside of somebody's authority. Even the pastor is under some sort of accountability.
3) The pastor is a servant of Christ. When a church calls a pastor it has to look at the pastor not as the employee of the church but as the servant of Christ, so He is under Christ's authority. When a church pays a pastor it is not to be looked on in the same way you look on your pay check. A pastor is supported by a congregation so that he can carry out the work that Christ has for him to do. That is the difference. However, this does not mean that he is not accountable to a local congregation.
4) A pastor-teacher is going to be accountable to a local congregation on the basis of the constitution of that local church. There are also guidelines listed in passages such as Titus 1, 1 Timothy 3:1-7, which define what it means for a pastor to live a life that is above reproach.
5) The pastor's responsibility is to study and teach, and this is what comes out in the next clause in 4:1: "stewards of the mysteries of God." The word translated "steward" is from the Greek word OIKONOMOS [o)ikonomoj], a compound word, OIKO = house; NOMOS = law. OIKONOMIA [o)ikonomia], which is a form of this word, is the word from which we get our word administration or dispensation. So dispensation has to do with the idea of stewardship or administration. And an OIKONOMOS is a steward, in other words to manage—he is given certain responsibilities in the household to manage—and he was the household administrator. So the first phrase, "as a servant of Christ," emphasizes the position of authority that God has given the pastor-teacher, and the second indicates his responsibilities in that position. He is a steward of the mysteries of God. This is the word MUSTERION [musthrion] used to refer to the revelation that is given in the New Testament that had not been previously revealed. In this context that refers to doctrine related to the church age and the spiritual life of the believer in the church age.
1 Corinthians 4:2 NASB "In this case, moreover, it is required of stewards that one be found trustworthy." The word translated "trustworthy" is PISTOS [pistoj] which has to do with being faithful. He is faithful to his responsibilities. So if a pastor is a manager or administrator of the doctrines of the New Testament then what God is holding him accountable for is faithfully teaching and communicating the doctrines of the Word of God.