John 1:35-37 tells us that one of the first two followers of Jesus was Andrew. The other is not named though we tend to believe it was the writer himself, John. Andrew then recruited his brother, Simon Peter, saying, "We have found the Messiah, which is, being interpreted, the Christ" (John 1:41). This was the straightforward way Jesus gathered his first disciples. Luke gives more background before the calling telling us that Jesus had already begun preaching and becoming widely known in the region, first around Nazareth, and then in the north near the coast of the Sea of Galilee: "And came down to Capernaum, a city of Galilee, and taught them on the Sabbath days. And they were astonished at his doctrine: for his word was power" (Luke 4:31-32).
Note Luke's historical reference: "they were astonished at his doctrine." The word "doctrine" means, very simply, teaching. Jesus' teaching always astonished people. The fact that it does not astonish us tells us a lot more about us than it does about Jesus. I think we cease to be astonished for several reasons: (1) We have heard these stories since childhood and know them too well. (2) We have tamed the stories to fit into a context that is nothing like that of the Bible. (3) We have actually paid so much attention to other things about Jesus (like debates over his nature) that we have not allowed his stories to sift and change us deeply. Could it be that we do not know the teaching of Jesus as much, or as well, as we think we do?
The Gospel of Mark is considered the oldest of the four Gospels. Mark, not an apostle like Matthew and John, is believed to have been Peter's close associate. Tradition suggests this Gospel was written under Peter's direction. It is the shortest Gospel and a great deal of it is repeated in other places thus prompting modern scholars to see its impact on the whole story.
Matthew provides the transition between the call of the first disciples away from their profession as fishermen to become fishers of men (Matthew 4: 23-25).
What amazes me is this: Jesus actual teaching is the least known and least understood part of his ministry. The church has always said the main teaching of Jesus was that he was the Son of God, the Creator and Judge of the world. Modern scholars tend to downplay this suggesting that the church made up this part of Jesus' teaching. This makes no good sense at all. The remarkable thing about this man is found in what he teaches about himself and the kingdom of God. C. S. Lewis was correct when he said in Mere Christianity that Jesus' claims to be the Son of God are either evidence of madness, a lie or clearly the truth. Unless these teachings are the truth then he cannot be the "good moral teacher" that many liberal critics still want him to be.
The very best way to grasp the teaching of Jesus is to read the Gospels again and again. Allow the "big picture" to grip you as you read. You will be amazed there is no doubt about it.
I believe the central truth Jesus taught, besides the revelation of who he was, is found in the Sermon of the Mount and the parables that reveal some of the same truths again and again. In short, the teaching of Jesus is about the kingdom of God. Jesus' hearers were looking for a new world order, a delivery from the oppression of the Romans. In the Sermon on the Mount they discovered that he was not a Zealot or a revolutionary. He is filled with zeal but it is for a kingdom-of-God lifestyle, not for overthrowing the government. The most powerful expression of this point occurs in Matthew 5:17-20, a passage that has intrigued and stretched me all my life. I have preached and I am still not sure I have exhausted the meaning. I do know that Jesus is not attacking the law of Moses but teaching it in a new way. That is self-evident. The other self-evident truth here is that Jesus wants his followers to exceed the efforts of the Pharisees to be holy. This holiness is central to his kingdom but it is not found in external customs but in conformity to God's law by the Spirit.
The Holy Spirit is the key to obedience in the kingdom of Heaven. The lifestyle we are called to by the teaching of Jesus cannot be undertaken without the power of the Spirit. Going the extra mile to solve grievances, bearing the burdens of others and making our words truthful all need divine power. We dare not attempt to live by any other means.
Matthew tells us that when Jesus finished this teaching the people were astonished. He taught them as one who had authority. He personifies a new covenant, a whole new arrangement with God whereby a person can live in obedience to God by the power of the Spirit.