What does Mark 5:15 mean?

Unlike the pig-herders, the people who come from the towns and countryside are more amazed by the freed demoniac than concerned over the fate of the pigs. The man has been a well-known figure in the area. Luke 8:29 explains that he had often been set under guard, but he would break his shackles and chains so often the people drove him into the wilderness.

Now they see this man sitting in his right mind, fully dressed, and they are afraid. "Afraid" is from the Greek root word phobeo and means to be terrified to the point of flight. They aren't afraid that the man will revert to his former behavior; they're afraid of the awesome power it took to free him—as the disciples were when Jesus calmed the storm (Mark 4:35–41).

Although the man's previous behavior gives them an exceptional example with which to compare the man's current condition, the crowd's behavior serves as a reminder to us. Human shackles and chains and guards cannot contain the destructive forces inside us. Our sin nature condemns us as wholly as any demon possession, and there is nothing in the human realm that can free us. Only the power of Jesus can set us right, put us in our right mind spiritually, and clothe us in righteousness (Isaiah 61:10). That awesome power is fearsome, but we can trust that the One who wields it works ever only for our good (Romans 8:28).