An important theme running throughout the Gospel of Mark is Jesus being rejected by the very people who should accept and support him. His family thinks he is crazy (Mk 3:21), his hometown people think he is a fraud (Mk 6:1-6), his disciples flee from him at the moment he needs them most (Mk 14:50), and even God seems to have abandoned Jesus (Mk 15:34).
Not all of these rejections are what they appear to be. Nevertheless the real suffering of Jesus begins early with these rejections and continues on to the very end.
1) Jesus returns to Nazareth. This story depicts the first time Jesus returned to his hometown of Nazareth after he had left. No one knew why he left. Rumors had circulated that he went up north to Capernaum where he was engaged in a healing ministry accompanied by preaching. He had not done any of that while he lived in Nazareth. One could image that this return would generate a certain amount of interest coated with a good bit of skepticism.
2) Teaching in the synagogue. Jesus is portrayed here as being a traditional Jew who attends the Sabbath synagogue service. On this occasion he is teaching in the synagogue. Those who heard him were astonished. To be astonished is not always a positive response. We can be shocked, upset, and insulted just as much as being impressed and favorably disposed. Obviously Jesus took his hearers by surprise. This is not the person they remember when he was living beside them in Nazareth. Their response seems coated with skepticism as if they think he is a fraud. After all, everyone knows who Jesus is (or they think they do). He lived down the street with his family and he was nothing special, just ordinary like everyone else.
3) A prophet without honor. Jesus detects the hostility of his hometown people immediately. He quotes for them an old wisdom saying that was popular among many people. Prophets are accepted every place except in their own home and by their own people. It is still quoted today. Jesus of Nazareth, the Messiah, and the Son of God is right in the midst of his own people and they do not have a clue.
They reject him. He is amazed by their response to him and their lack of faith. Without faith Jesus cannot fulfill his deeds of power even for his own people.