Mark stressed that Jesus performed miracles in response to faith. Here we see the other side of that coin. The Nazarenes" refusal to believe in Jesus resulted in His not being able to do miracles among them. Unbelief limits God"s working (cf. Acts 14:9-10). This is the only time Mark said that Jesus was amazed. He marveled that the unbelief of the Nazarenes was as strong as it was. This implies that their decision not to believe was in spite of evidence adequate to lead them to another conclusion. They were morally blameworthy for their unbelief. [source][source][source]
"The people of Nazareth represent Israel"s blindness. Their refusal to believe in Jesus pictured what the disciples would soon experience (cf. Mark 6:7-13) and what Mark"s readers (then and now) would experience in the advance of the gospel." [1][source]