Mark 6.1-2: He went away from there and came to his hometown, and his disciples followed him. (2) And on the Sabbath he began to teach in the synagogue, and many who heard him were astonished, saying, “Where did this man get these things? What is the wisdom given to him? How are such mighty works done by his hands?” (ESV)
Just prior to the verses above, Jesus had worked two miracles, one of which was raising the daughter of Jairus from the dead. Right after this miracle Jesus came to his hometown. So in this case Jesus is in the synagogue he attended when he was a child and young adult.
And after Jesus taught his lesson on the Sabbath, the people of his hometown demonstrated their surprise that it was possible for Jesus to be such an extraordinary teacher of scripture. And they were not polite about it. Reading these two verses above gives the impression that the people responded soon after Jesus finished his teaching.
But what is built into their amazement is the confirmation on their part that Jesus was in fact an authoritative teacher and he was a person of great wisdom, and on top of these things he worked miracles. The people were not debating these attributes. Certainly they had heard the reports of Jesus the teacher and worker of miracles in other locations, but when they saw him with their own eyes, they were astounded.
The people of Jesus’ hometown did not try to refute the reality of what Jesus actually was doing. They appeared to have difficulty believing such things could be from him.