This story is frequently discussed because it is so clearly a symbolic story inserted to teach and comfort rather than relate an actual event. Here are some thoughts I am borrowing from various sources while researching this:
To start with there is no such place near or opposite Galilee in any direction. The only town in the Israel of the time that was spelled anything like Gerasene was thirty miles from the nearest water so the swine would have had a long run. So we need to look at the story again and when we do we find it is not an actual event in the historical life of Jesus but an event in the spiritual life of the early church that owes its existence to Jesus.
Jews hated nudity and wouldn’t take part in the athletics of the day because the runners were naked. No surprise then in Luke’s story that the man possessed by demons wore no clothes and lived among the remains of the dead, a place that frightened the Hebrew people. Who then does this man represent?
We get the clue in verse 30 when his name is given as Legion. The common name for Rome, a military dictatorship, was ‘Legions’ because that was what the army was, legions of soldiers. As far as our story is concerned the man had legions of demons because anyone and everyone who stood in opposition to Rome considered Rome to comprise legions of evil ways. As the story says, “for many legions had entered him”, it was the perfect description.
At the time this was written, the early church was making inroads into the Roman psyche. At verse 28 the demonic man says to Jesus, “I beg you do not torment me” for Jesus had commanded the unclean spirit to come out of him. The early Christian Church was on a crusade to reform Roman society and with some delight the author is saying that the old society was begging for mercy as Christianity swept on, changing structures and people’s thinking.
In our story we then have a reference to previous efforts to control Rome. “He was bound with chains and shackles but he would break the bonds and be driven by the demon into the wilds.” Other armies, it is saying, have tried to tie up Rome and nations have rebelled against the Roman rule and maybe the writer was thinking of the attempt by the Zealots and Jerusalem Christians in their war against Rome that destroyed the Jerusalem Temple in AD70, but in every known attempt to overthrow it Rome soon broke free of the attempt to restrain it and resorted to even more violence and evil to maintain control over their victims – but against Jesus the might of Rome, it seems, had no answer.
Where then are the evils of Rome to be banished?
To answer that we must consider one of the things that marked Hebrews out from the rest of their Semitic neighbors. They had different eating habits, their diet was different, and what is significant, they never ate pork. Over the course of time pork and pigs came to represent all that was bad in their neighbors and in foreigners so when they had to get rid of evil from Rome, to send it into pigs and have them hurtle into a death by drowning was a sweet justice.
The swineherds of the story are the pork-eating foreigners who become alarmed at the success of the Christians and tell everyone what is happening but that also just gives greater publicity to the fact that those who have converted to Christianity live, not just better lives, but wholesome healed lives.
God Bless