They came to the other side of the sea, to the country of the Gerasenes. And when he had come out of the boat, there met him out of the tombs a man with an unclean spirit, who lived among the tombs; and no one could bind him any more, even with a chain; for he had often been bound with fetters and chains, but the chains he wrenched apart, and the fetters he broke in pieces; and no one had the strength to subdue him. Night and day among the tombs and on the mountains he was always crying out, and bruising himself with stones. And when he saw Jesus from afar, he ran and worshiped him; and crying out with a loud voice, he said, "What have you to do with me, Jesus, Son of the Most High God? I adjure you by God, do not torment me." For he had said to him, "Come out of the man, you unclean spirit!" And Jesus asked him, "What is your name?" He replied, "My name is Legion; for we are many." And he begged him eagerly not to send them out of the country. Now a great herd of swine was feeding there on the hillside; and they begged him, "Send us to the swine, let us enter them." So he gave them leave. And the unclean spirits came out, and entered the swine; and the herd, numbering about two thousand, rushed down the steep bank into the sea, and were drowned in the sea.
The herdsmen fled, and told it in the city and in the country. And people came to see what it was that had happened. And they came to Jesus, and saw the demoniac sitting there, clothed and in his right mind, the man who had had the legion; and they were afraid. And those who had seen it told what had happened to the demoniac and to the swine. And they began to beg Jesus to depart from their neighborhood. And as he was getting into the boat, the man who had been possessed with demons begged him that he might be with him. But he refused, and said to him, "Go home to your friends, and tell them how much the Lord has done for you, and how he has had mercy on you." And he went away and began to proclaim in the Decapolis how much Jesus had done for him; and all men marveled.
Mark 5:1–20 (RSV)
The demons always know. Hardly any human comes close to grasping who Jesus is. The demons always know. Perhaps since they had once been in the presence of God, the clarity and perfection of His glory could never be erased from them.
All humans could see was how Jesus' actions affected them. Certainly, the possessed man was grateful for his healing. The swineherds are upset about their loss. Who wouldn't be? The townsfolk were upset because they couldn't understand how or why Jesus intervened in their lives. Yes, it was nice that the possessed man was no longer a threat to them. Still, it was a change from the normal.
Then the begging, the demons beg Jesus to allow them to go into the pigs. I don't recall anywhere in the New Testament where Jesus destroyed the demons. He cast them out, but He allowed them to continue to exist. Jesus never destroyed anyone, though He could have annihilated the demons. Perhaps they, like we, are worth redeeming.
The townsfolk begged Jesus to leave because they were afraid. They were fearful because Jesus healed the man. They were afraid because the swine were lost. They were worried that they would have to look at their world with new eyes. They wanted Jesus gone. Who could tell what He might do or ask of them?
The man begged Jesus to go with Him. He had a new life and wanted to be with the One who had given it to Him. Jesus said, 'No' to his request. Jesus' purpose for the man was to go and tell everyone, starting with his friends, what God had done for Him. The man did just that. He told everyone in the area how God had changed his life.
Luther once wrote that we are all beggars. We come to Jesus with our demons, our sin, and our broken lives, and He heals us. We have nothing to offer, nor could we offer anything. We come fearful, angry, confused, and uncertain we deserve anything at all from God.
Jesus does not destroy anyone of us. His heart longs to heal each of us, even the most wretched. He has done it for others. He will do it for us as well.