Mark 1:24

The man cried out, but it was really the demon speaking through him. This is clear because Jesus replied to the demon (Mark 1:25). The words "what do we have to do with you" represent a Hebrew idiom that introduces conflict (cf. Mark 5:7; Joshua 22:24; Judges 11:12; 2 Samuel 16:10; 2 Samuel 19:22). Today we might express the same thought by saying, "Why are you meddling with us?"

The demon recognized Jesus, and it knew about His mission. It was common for the Jews to identify a person by his place of origin (cf. Mark 10:47; Mark 14:67; Mark 16:6). In Jesus’ case this was Nazareth. We could just as accurately translate the words rendered "Have you come to destroy us" as a statement of fact: "You have come to destroy us." In either case the demon expressed dread. Clearly this demon recognized Jesus as its judge. This showed Jesus’ great authority.

By calling Jesus the Holy One of God the demon testified to His empowerment by the Holy Spirit, the enemy of all unclean spirits. This title also probably implies belief in Jesus’ deity. The title "Holy One" was a popular designation of God in the Old Testament. Isaiah called God the Holy One about 30 times (Isaiah 1:4; Isaiah 5:19; Isaiah 5:24; et al.). Whereas people referred to Jesus as "Lord" (Mark 7:8), "teacher" (Mark 9:17), "Son of David" (Mark 10:47-48), and "master" (Mark 10:52), the demons called Him "the holy One of God" (Mark 1:24), "the Son of God" (Mark 3:11) or "the Son of the Most High God" (Mark 5:7).