In short
The servant’s paralysis, coupled as it was with terrible suffering and imminent death, was probably the result of demonic attack, which only Jesus could counter.
The servant, lying paralyzed in his house, is in great torment. He was apparently suffering from a sudden demonic attack, which immediately caused paralysis. The demon is so strong that the man is being tormented to the point of death. The fact that a powerful man such as the centurion approaches Jesus in a seemingly hopeless situation shows that he acknowledges him as having ultimate power.1
6 “Lord, my servant is lying paralyzed at home, suffering terribly.”