God's Power over Evil
Confronted by two violent, demonised men, Jesus and His disciples stepped from their boat onto an otherwise deserted beach. The demons recognised who Jesus was and were in awe of His power over them. They were reluctant to leave the men they had been manipulating and did not want to be sent to hell. If they were to be exorcised, they preferred to make their home in pigs.
Jesus chose to allow them to go into the pigs, not because they had the authority to demand their own solution, but because Jesus wanted everybody to see the devastating power of evil - and His ability to deliver people from its grip. Satan's authority, which had dominated the men, was clearly seen as the demons propelled the pigs to run to their destruction. On the other hand, the men were transformed from being naked and terrifyingly violent, to being clothed and peaceful with a full rational mind (Luke 8:35).
The local townsfolk were frightened to see this expression of power and also to realise that their livestock (and livelihood) had disappeared into the sea. Jesus was not welcome any more. They had tolerated the disturbed men who largely kept to themselves, but had no idea of the potency of evil so close to them. Neither did they realise the evil within themselves which generated the same reaction as the demons, "Go away, Jesus".
The presence of Jesus is either welcomed or resented. Most people, who have no idea of the sin within them, are content to tolerate Jesus until He demonstrates his power close to them. It may be the transformation of a close family member, colleague or friend who has repented and received Jesus. All of a sudden the presence of God in that new believer makes some others very uncomfortable - as if Jesus might be a threat to them. Sometimes the demonstration of God's power produces such a strong reaction that they want the believer to leave or at least stop talking of what the Lord has done. When that happens, be encouraged. It is a sign that the Holy Spirit is at work convicting your friend of the sin they do not know is lurking within them.