I'm an atheist. What weight do you think that holds for me?
It is all superstitious nonsense. Pork is tasty. When jebus drove a herd of pigs over a cliff for spurious reasons, one must wonder why jews were herding pigs. Or why there were any herds of pigs in the ancient levant to drive over any cliffs. Surely it couldn't be subsistence agriculture? Heaven forfend.
Along similar lines, consider this question.
Who was the prodigal son working for when he took care of pigs?
Same problem. The Hebrews did not raise pigs. So where did this herd of pigs come from? And why couldn't the prodigal son share some of the slop with the pigs? Apparently, he wasn't allowed any of the food fed to the pigs. Nor could he share in the pig flesh. The pig owners could have paid the fellow in pork. Having rejected Hebrew tradition by leaving the family, he could have eaten the same food as the unnamed owners. So apparently this poor Hebrew worker was being starved by the insensitive owners for the sake of their bacon. Furthermore, why did the Bible even mention the pigs in this story? Yes, he was starving. However, you can starve even easier when you are unemployed. So the Bible could have said that he was unemployed, or harvested grain, or worked in a mine, or a dozen other places where poor people go. So maybe the parable is making a political point when it says that the prodigal son envied the pigs.
It was the Romans, or people working for the Romans, that were herding the pigs. So Jesus's miracle could be interpreted as a political statement against Roman occupation. It could be interpreted as saying, 'Don't adapt the customs of the Romans'. However, that doesn't explain why Jesus would be especially down on pigs.
Marvin Harris hypothesizes that pigs are 'unclean' in desert societies because they are ecologically inefficient sources of nutrition. They eat the same food that human beings eat. So if some of the calories of work energy available in any food are wasted for human beings when it is devoured through a pig.
Pigs are more useful in climates that have forests because the pig can get food from places where humans beings can't go. Pigs are useful in temperate climates because pigs reproduce faster than most livestock. So they concentrate free energy into a small volume in a very short time. One has to eat a lot of apples in order to get the same nutrition as an ounce of pig fat.
Children grow larger and stronger on meat then they do on bread and fruit. You can support more people on a diet of bread and fruit, but the adults will be more lightweight than on a diet of meat. So if you are the military sort of society, you want to get your calories from meat. Cattle and sheep are good sources of calories, but they don't grow and reproduce as fast as pigs. Further, cattle and sheep eat grass. Grass can not be directly eaten by humans. So unless you have lots of grassland available, as some of the Middle East people had, you need pigs. So a soldier is going to find pig nutrition a lot more useable than cattle and sheep in the arid climates.
If Marvin Harris is correct, then a herd of pigs would have been specifically offensive to the poor people in this arid environment. Poor people would resent the good food (e.g., meat, fruit, wheat) being fed to the pigs. The Romans would get most of the pig meat anyway, because it is more expensive. The Romans had to take food from their poor subjects to feed their pigs!
Marvin Harris points out that this is a key part of the 'Prodigal Son' story. The prodigal son leaves his father (i.e., his tradition) to become a pig herder. However, he is not allowed to eat any of the food that he is obliged to give the pigs. He envies the pigs for the slop that he is forced to give them!
So when Legion (Roman Legion?) is possessed by demons, Jesus passes them on to the food of their oppressors. He drowns the pigs. By doign so, he was indirectly feeding the poor Hebrews that are ruled by the Romans. With fewer pigs around, the slop would be available to the poor masses (including the prodigal son).
I was wondering whether the name Legion really is a cognate of the Roman word legion. I doubt that it would have been a common name for Hebrews, or even other Semites in the region.
Jesus could have banished the demons into an abstract Hell, or dragged them into the sky, or buried them, or buried the demons. The choice of cursing pigs seems rather arbitrary from the standpoint of modern religion.
I note that a lot of Christians don't see the Romans of ancient times as sinners. They refuse to believe that Jesus had any problem with the Romans. In their way of thinking, the Roman soldiers were merely being forced to persecute Jesus by those mean Jews.
So they don't like to analyze why Jesus expressed himself the way that he did. They look at me crazy when I ask, 'Why drown the pigs?' Or even, 'Who was the Prodigal son working for?"
Religious people prefer to interpret the stories in terms of their immediate culture. They don't like to ask questions about the common people that are the cultural background of the Bible. Secular anthropologists are a little better. Secular scholars try to find out how people of different cultures and classes interacted. Religious scholars try to ignore the common people whenever they could.