It did not take very long for news of the Gerasene demoniac's healing to spread, for the herdsmen who looked after the pigs quickly told everyone about what had happened. Naturally, this sparked the curiosity of the locals who knew the formerly possessed man. So, many people came to see the evidence for themselves (Mark 5:14–15).
One would think that this miracle would have been the cause of great joy among the local citizens. Certainly, there were people in the crowd who were the healed man's relatives and friends, and at least they had reason to rejoice. Yet, the response of the people was one of great fear, and they begged Jesus to leave the area (vv. 15–17).
Their desire for Christ to leave may have been based partly on the loss of the pigs, as Mark 5:16 says the thoughts of the people were on the swine. The death of the pigs was a great financial loss, so it may be that the people feared that Christ's remaining there would be a blow to their livelihoods. We are reminded of the riot by the Ephesian craftsmen when Paul's preaching led many Ephesians to give up worshiping false gods and purchasing idols (Acts 19:21–41).
However, the fear of the loss of income was not the main reason why the people begged Jesus to depart. As in the account of the calming of the storm, the witnesses feared Christ, but those who saw Jesus calm the sea did not call upon Him to leave (Mark 4:35–41). This can only mean that the disciples on the boat had a greater insight into our Lord's character. They knew His divine power and His mercy. The same was true of the Gerasene demoniac. But the crowd who came out to see the formerly possessed man only knew His divine power. John Calvin comments: "We learn how wide is the difference between the knowledge of the goodness, and the knowledge of the power, of God. Power strikes men with terror, makes them fly from the presence of God, and drives them to a distance from Him: but goodness draws them gently, and makes them feel that nothing is more desirable than to be united to God."
Fallen creatures tremble in abject fear at the thought of the Lord's power and cannot endure His presence for long when they have not relied on His mercy. He is terrifying to all who do not know His forgiveness. As Dr. R.C. Sproul says in his commentary Mark, "When the Holy One is manifest in the midst of unholy people, the only appropriate human response is dread."
Fallen people reject God not because they do not know His power. Instead, they reject Him because all they know is His power and purity. People who have no apprehension of the extent of His goodness, which is displayed in His extension of mercy to repentant men and women, tremble in terror because unholiness cannot bear the presence of holiness. But if we are in Christ, we have been forgiven and can stand before God in safety.