“Now a large herd of swine was feeding at some distance from them. The demons begged him, “If you cast us out, send us into the herd of swine.” And he said to them, “Go!” So they came out and entered the swine; and suddenly, the whole herd rushed down the steep bank into the sea and perished in the water” (Matthew 8:30-32).
This account is offered in Matthew 8, Mark 5, and Luke 8. The accounts differ slightly in the details, but the broader message is the same in each. The context of the passage is Jesus coming upon some number of (one or more) demon-possessed person(s) to cast out the demons that are tormenting them. The demons acknowledge Jesus as the son of God and beg him to let them go into a herd of nearby pigs instead of destroying them. Jesus then commands the demons to leave the person(s) they are tormenting, and so they go out and enter into the pigs. The pigs then run down the hill into the sea and drown. And the person(s) that had been tormented by the demons become cured.
The demons (or “evil spirit” in Luke) are described in the Matthew and Mark accounts as violent and causing their host to be violent, whether person or pig. The demonic instigators (or evil spirit) of violence begged Jesus for mercy and so instead of casting them into the abyss, he merely commanded them to get out of their host, at which point they entered the pigs and caused the pigs to run violently down the hill into the sea to drown (Mark 5:13). It wasn’t Jesus that caused the pigs to drown but instead the demon(s), the instigators of violence. Jesus merely had mercy on the demons when they begged him for mercy, just as he had mercy on the person(s) being tormented by the demons whom Jesus healed by sending out the demons.
Jesus did not cast demons into pigs to harm the pigs. He cast them OUT of the man they were tormenting and they went into the pigs of their own will after begging Jesus not to cast them into the abyss (Luke 8:31).
One takeaway from this story is that even the demons acknowledge Jesus as the son of God (Mark 5:7). Thus, mere acknowledgement of Jesus as son of God is not enough; we must also follow him and live by our faith. Another takeaway is that we should be merciful, just as our Father is merciful (Luke 6:36). Our mercy should not only extend to our friends, our neighbors, and those who love us – but also to the marginalized, the powerless, and even our enemies. If Jesus is merciful even to demons when they beg him for mercy, how much more merciful should we be toward anyone under our authority – including an animal that cries out to us for mercy?