Satan knows his Limits
Jesus and His disciples arrived by boat onto a lonely shore, but soon two men joined them. They were extremely violent and had such a reputation of being dangerous to travellers that nobody took the coastal path in that area. So it seems that Jesus had deliberately chosen to encounter the men, even though they were being manipulated by Satan ... more than that, he encountered them to show that His power was greater than the domination of evil.
As the men spoke, demonic voices came out of their mouths. These men had never met Jesus before and probably had no contact with the crowds who have heard His teaching or seen His miracles. Yet the words were clear - they knew who Jesus was and understood his identity more clearly than the disciples. The words coming from the men's mouths described Jesus as the Son of God: previously in this Gospel it was only Satan who addressed Jesus in that way (Matthew 4:3-6).
The demons also knew their destiny - to be tormented, knowing their failure to depose God, and confined so that they can no longer tempt human beings into rebelling against God (Revelation 20:10). They also knew that there was a time when this would happen and were bitterly resisting the authority of God until that time. Meanwhile Satan and his demons are furious and fill people with wickedness (Revelation 12:12), like the men on the sea shore who were extremely violent.
Satan's time is limited and although He tries to stop people reaching Jesus, the Lord has authority over him ... and he knows it. If the demonised men knew the identity of Jesus, and the wind and waves became still at His command, why did the disciples not have more faith (Matthew 8:23-27)? Like the disciples, we are often so blind because we look for power and authority in the wrong places: in money and power, the approval of others and the success of our career. The authority of Jesus seems so often to come second to our own actions and desires because we have lost sight of who He is (Matthew 8:27). When we fail in our plans we may become angry. Let us stop and confess our selfish pride ... and simply accept the authority of Jesus.