A distinction between the role of pastor and the role of teacher is common in the modern church. This arises from a false understanding of what the New Testament means by "teaching". The modern mind tends to think of teaching as something that happens in a classroom. We mostly think of teaching as a transfer of information and skills. Modern teaching is usually a process whereby an expert passes on information to a group of students. They are quite free to ignore what is taught.
The modern church has taken the classroom model into the Sunday worship meeting. The problem is that when people hear teaching week after week, they assume they are growing because they know more, but in reality, their practice, behaviour and character are largely unchanged. Modern Christians get significant theoretical knowledge, but very little practical experience. This is why I say that most preaching/teaching does not add much value. It makes people feel they are getting ahead (knowledge puffs up) when they are doing very little of eternal significance.
Teaching and Discipleship
For the early Christians teaching was something quite different. They saw it as an activity involving personal direction and an exercise of authority. It took place within a relationship where the teacher had authority over the student. A student would submit himself to a teacher, whose lifestyle he admired. His aim would be to learn the way of life, and the truths which underlay it. So a teacher did not just give his views. He laid out what he expected the student to believe, and the way he expected him to live. So teaching in the New Testament was more like what we call "discipling". It included the formation of character.
We can see this in the way that Jesus taught his twelve disciples. He did not just impart information to them. By living in close proximity with them for three years, he developed a strong relationship with them. They submitted to Jesus and carried out all his instructions. He had complete authority over them. In this way, he formed their lives into a likeness of his own.
Jesus used a master/apprentice model, where the apprentice lived and worked with the master, copying what he was doing and learning while he was doing it. The master gave information to the apprentice, but it made sense because it related to what they were doing in the workshop. The parable of the sower makes more sense when you have been sent out two by two to share the gospel.
And throughout the New Testament, teaching takes place within a similar pastoral relationship. This means that the "pastor and teacher" is one ministry. Every teacher is a pastor, and every pastor is a teacher (1 Timothy 3:2).
No Modern Preaching
The first believers met in homes for fellowship, so clearly, they started doing discipleship in Jesus, way. They knew that if people got together in the way he had trained them, the Holy Spirit would teach them (1 John 2:20).
When the apostles were in the temple preaching, they seemed to be mostly doing evangelism in the way that Jesus did it, by confronting the religious leaders, and calling the people to switch allegiance and follow him. I think this is the proper role for preaching. All the public messages recorded Acts were evangelistic, calling the people to change their ways and follow Jesus: Peter, Acts 2:14-40; Peter and John, Acts 3:12-26; Peter, 4:8-12; Peter and the Apostles, Acts 5:29-32; Stephen, Acts 7:2-53.
There is no record in Acts of a mass-discipling type sermon that is so common on Sunday morning in modern churches. It may have been needed in previous generations when many people did not have access to books or could not read. However, it is a sub-optimal method that should not be normalised. If people do need more theological information, there is plenty of top-class teaching available on electronic media, so making teaching the focus of Sunday meetings is not as relevant as it was in the past.
Jerusalem Problem
The early Church seemed to get into a bit of a mess in Jerusalem. Instead of following Jesus, example and being sent out into the world, Peter, James and John stayed in Jerusalem. They seem to have gathered a large congregation of people who enjoyed listening to their teaching. These people had no means of supporting themselves (offerings had to be sent from other churches to keep them going) because they were not doing anything of value. God had to send persecution to shock them out of their comfortable complacency (Acts 11:19-21) and get them out into the world.
I find it interesting that God had to get Paul to get Jesus, model of making disciples and quickly sending out the best to start a new church in a new place fully operational again. The Holy Spirit used Paul's experience to get a description of the apostolic way working in practice into the scriptures. In contrast, Peter seemed to create problems whenever he did go out into other places (Acts 10:44; 15:20; 21:20-25; Gal 2:11-14). See Governmental Apostles and Centralised Finances.
I presume that the other apostles (like Thomas who possibly went to India) were not mentioned again in Acts, because they followed Jesus, command to go out into the world and make disciples.
I have wondered how Paul learnt to be an apostle in Jesus's way, given that he was not discipled directly by Jesus. He was a good listener to the Holy Spirit, but that was probably not enough. I presume that he had learnt from Barnabas, who was an early disciple in Jerusalem, and possibly taught well.
Back to the New Leadership Model.