In Luke 8:22 Jesus wanted to go to Gerasenes (Luke 8:22), which is across the lake from Galilee (Luke 8:26). On a map for that period, the territory would have been called Gaulanitis. When Jesus went ashore, he was immediately met by a man, a citizen of that city. That man was also a demoniac and quite out of his mind (cf. Luke 8:35). He wore no clothes and lived presumably in one of the caves among the tombs in that place (Luke 8:27).
When the demoniac saw the Lord (cf. Mark 5:6), he came running to him (cf. Matthew 8:28), no doubt in order to do violence to him or chase him away. However, as he approached Jesus, the demoniac recognized him and cried out that Jesus had no business there, seeing they had nothing in common (Luke 8:28). Nevertheless he fell at Jesus feet, worshiping him and asked for mercy. In other words, he implored Jesus not to torment him before his time (Luke 8:28; cf. Matthew 8:29). Mark tells us that the demoniac even asked Jesus to swear to God that he wouldn’t harm him (Mark 5:7).
Why would the demoniac ask such a thing? Had Jesus already done something to him as he came running (Luke 8:29)? The text tells us that, as he approached Jesus and the disciples, somehow the demoniac recognized Jesus. When this occurred, the demoniac began shouting that he and Jesus had no business together, so why had Jesus come. While the demoniac was still shouting, Jesus commanded the unclean spirit to come out of him, at which time he fell at Jesus feet, pleading that the Lord wouldn’t kill him.
It seems that all demoniacs are able to recognize who Jesus is, that is that he is the Messiah, the Son of God. There is no reason given in the Scriptures that would lead us to believe they know more than this. Nevertheless, this demoniac believes that Jesus has come to judge him before his time. In other words, he knows Jesus is the Judge (Messiah), but he believes after death he will be in hell, a place of torment (Luke 8:28; cf. Luke 16:23). This is a Pharisaic doctrine, which cannot be proved in the Scriptures. The demoniac’s understanding, therefore, implies he is a Jew and not a gentile, as is usually supposed. Moreover, his use of a Hebraism in Mark 5:7 “I adjure you by God…” meaning “Swear to God…” points to a Jewish background.
It also appears the demoniac was afraid Jesus would kill him. In Mark 5:10 he pleaded with Jesus that he wouldn’t send him out of the country (G5561), meaning out of the land (of the living). Luke 8:28 tells us the man was afraid Jesus intended to send him into the deep (G12). This same Greek word (G12), when used in the book of Revelation, it is translated as the bottomless (pit), and refers to the place of the dead (cf. Romans 10:7).
The text says the unclean spirit had often caught (G4884) this man. In other words, the man hadn’t always been controlled by the unclean spirit, and in those times the townsfolk might have been able to capture him (Luke 8:29; cf. Mark 5:3-4). However, once he was caught (G4884) by the unclean spirit, he could not be controlled by men, not by the man himself nor by any other man (cf. Acts 27:15 where the same Greek word is used to describe the storm at sea). So, any attempt to tame or rehabilitate the unclean spirit within the man had proved unsuccessful.
This scene is a picture of the carnal mind within man (cf. Romans 8:7). The carnal mind is that part of us which cannot be redeemed. It must be replaced with a new spirit. The carnal spirit cannot be made subject to God’s authority, and to give ourselves over to this spirit renders us useless for the work of God (Romans 8:8).
 See Revelation 9:1-2, 11; 17:7-8; 20:1, 3