Who was speaking?
The man ran to Jesus and worshipped, but the words that follow are associated with the unclean spirit Jesus was commanding to come out. The account moves between the suffering man and the demons that had taken control of him.
When Jesus asked the spirit’s name, it answered “Legion: for we are many.” The plural answer explains the extraordinary violence and misery described in the passage.
Why the demon recognized Jesus
Recognition is not the same as saving faith. The unclean spirit knew Jesus’ identity and authority but remained opposed to Him. James similarly says that demons believe there is one God and tremble.
Calling Jesus the Son of the most high God shows that the spiritual powers recognized an authority the surrounding people were still learning to understand.
What “torment me not” means
The demons knew that judgment awaited them and feared that Jesus would impose torment. In the parallel account they ask whether He has come to torment them before the time.
Their plea cannot bind Jesus. He permits them to enter the swine, after which the herd runs into the sea. The man is then found sitting, clothed, and in his right mind—a visible demonstration of Christ’s delivering power.