The demons begged to be allowed to enter the pigs. Christ (for whatever reason) granted their request. The demons entered the pigs, then the pigs stampeded and were drowned.
I don’t know why Christ would grant a request made by demons; but it wasn’t Christ who drowned the pigs.
Scripture was written for the sake of salvation.
Scripture was not written for the sake of historical accuracy, scientific accuracy, as a medical journal or as a commentary on the state of healthcare in first century Judea. The story of Jesus casting out the demons into pigs was written for one reason, given to us by God for one reason alone - for the salvation of our souls. That is the only reason why scripture exists, for the salvation of our souls.
We have to read Scripture like a Jew.
Pigs were unclean food according to the Jewish law of Moses. Also, Jesus was not within the borders of Judea when this incident took place but was in the pagan “Country of the Gadarenes” which was grecco-roman at the time. The name of the man who is posessed is also not given. When someone’s name is not given, it is often because they are representative of a nation or group of people. That’s how Jews wrote. They couldn’t just run down to the office supply store and get more paper. They wrote in ways that draw thier audience into the story. They wrote in ways which communicate lots of information with very few words under the assumption that the audience understood the details and background. The audience was Jewish.
The pagan grecco-roman “Man who is possessed” in the “Country of the Gadarenes” is the same style of writing as the “Woman at the well” in John 4. She represents the apostate nation of Samaria. First century Jews who read the accounts would have recognized the locations and would have understood the man posessed as representing the Gentiles and the woman at the well as representing Samaria. They would have recognized this because they had intimate and first hand knowledge of Jewish history, geography, culture, religion and politics.
The story of the pigs is a story about the Gentiles being brought into God’s family where previously only Jews had been allowed.
Jesus commands the demonic spirits which were the result of pagan worship to enter the unclean food which the pagan gentiles ate, and then both the food and the demons are destroyed.
The demons which resulted from the worship of false gods are gone. The unclean food which the Gentiles ate and the other practices which violate the laws of moses which the pigs represent are gone. The unnamed pagan grecco-roman man is free of the demon. The pagan people whom the unnamed man represents are cleansed, and brought into the the covenant family of God.
Earlier in Matthew 8, Jesus cures the Centurion’s servant. The centurion was a Roman. Again, it is a story of the whole world being brought into God’s covenant family through the work of Jesus Christ.
***Now there were some Greeks *
among those who had come up to worship at the feast. They came to Philip, who was from Bethsaida in Galilee, and asked him, “Sir, we would like to see Jesus.” Philip went and told Andrew; then Andrew and Philip went and told Jesus. Jesus answered them, "The hour has come for the Son of Man to be glorified. (John 12:20-23)
The unnamed Greeks “Wish to see Jesus”. Here John is telling us that the gentiles are beginning to accept Christ. Jesus’s response isn’t, “Tell them to come back later” or “What do they want?” Jesus’ response to the news that the Gentiles are seeking salvation through him is the recognition that his work on earth is nearing an end. He has been successfull. The seed has been planted and the Gentiles are beginning to seek him. His work is nearing completion.
Again, scripture isn’t a commentary on the first century Jewish understanding of medical science. Scripture was written for the sake of our salvation and no other reason, and looking at Scripture through the eyes of a first century Jew helps us understand it much better.
-Tim-