The different evangelists use different techniques to stress the greatness of God's power at work in Jesus. For example, in speaking of his miracles of healing a Gospel may stress how Jesus cured many people of many different diseases. The story from Mark's Gospel attains the same effect by stressing the seriousness of the possessed man's condition, and the reaction of the region.

A possessed wild man that people undoubtedly avoided and probably feared by his community made for an odd choice. Going from a maniac to a proclaimer of Jesus left people amazed.

And then a surprising reaction of the people of the region. "They began to beg Jesus to leave their district." An odd request to someone who had just performed a miracle.

Often the people who witnessed Jesus' miracles were astonished or amazed. But it is clear from the Gospels that this astonishment did not always lead to faith.

Of course, in God's providence, there are indeed cases where astonishment or wonder can blossom into real faith.