Question: When Jesus met the man called Legion the demons begged him not to torment them or send them back to hell and asked to be sent into the pigs. Jesus granted their request and when they had possessed the pigs they drowned in the sea. My question is, what happened to the demons after the pigs drowned? Were they released to possess other people? Where did they go?
Answer: Thank you for your question. The event you refer to is chronicled in Luke 8:26-29 (with parallels in Matthew 8:28-34 and Mark 5:1-20). I reference the Luke passage because Luke mentions the demons begging Jesus not to cast them into the Abyss. The story is fairly well known. Jesus comes into the region of the Gerasenes (or Gadarenes) and encounters a man who is possessed by a legion of demons. At the very sight of Jesus, the man with the demons falls down and recognizes Jesus for who He is, the Son of the Most High God. They beg Him not to torment them and not to cast them into the Abyss. Now that's an interesting word (the King James says, "into the deep" and the New Living Translation says "bottomless pit"). The word is a transliteration from the Greek (abyssos), and it means "bottomless, unbounded, the abyss." It occurs 9x in the NT, seven of those occurrences in the Book of Revelation. In ch. 9, the abyss is opened and a horde of demons escape to torment humanity in the end times, and in ch. 20, the abyss is where a mighty angel casts and binds Satan during the Millennium. It seems to be the abode of the demons where they are kept until the very last days. So, these demons are begging Jesus not to be cast there.
The rest of the story is also familiar. Jesus allows them to go into a nearby herd of pigs and the pigs run off a cliff into the lake and were drowned. Now your question, while interesting, is one we cannot answer definitively. We don't know where the demons went after the herd of pigs drowned. The reason we cannot answer that question is because the Bible doesn't tell us. Any answer I, or anyone else, can give would be speculation. What are the various answers to this question? Well, the first answer that comes to mind is that the demons were destroyed when the pigs died. Another answer is that after the pigs died, the demons were then cast into the abyss. The final answer is that after the pigs died, the demons were free to demonize someone else. There is some biblical evidence for the third answer. In Luke 11, when Jesus confronts some people about casting out demons, says in vv. 24-26, "When an unclean spirit goes out of a man, he goes through dry places, seeking rest; and finding none, he says, 'I will return to my house from which I came.' And when he comes, he finds it swept and put in order. Then he goes and takes with him seven other spirits more wicked than himself, and they enter and dwell there; and the last state of that man is worse than the first" (Luke 11:24-26 NKJV). But again, we're not explicitly told about the legion of demons from Luke 8, and what happened to them. So, where the Bible is silent, we should not speak authoritatively.
I will say this in closing. We should not see Satan and the demons as equal and opposite forces of evil opposed to God. God is the Creator; Satan and his demons are mere creatures. Recall how the demons begged Jesus not to torment them and asked permission to go into the pigs. They saw Jesus as the Son of the Most High God and their Creator. In the Book of Job, Satan cannot afflict Job unless and until God allows it, and even then, Satan could only afflict Job in the way God allowed. Furthermore, we know their end. When Jesus returns in glory at the end of the age, Satan and his demons will be cast into the Lake of Fire, which is the final judgment. So, Satan's fate is sealed. His doom is sure. While he may roam, as Peter says, like a roaring lion, we who have the Holy Spirit are held in the unbreakable grip of the Triune God.
I hope this helps.
~Pastor Carl