Scripture records a number of Jesus’ encounters with demon-possessed people. Two passages in Mark bring out an important truth from those encounters that is easy to overlook.
Mark 1:21-28 and 5:2-20 record the casting out of demons, which was a major aspect of Christ’s gracious judicial work (Acts 10:38; 1 John 3:8). Both passages feature demonic testimony to Christ as God’s judicial agent (1:24; 5:7).
In Mark 1, Jesus cast out an unclean spirit from a man in a synagogue. Before Christ rebuked the spirit and ordered him to come out (1:25), the demon cried out, “Let us alone; what have we to do with thee, thou Jesus of Nazareth? [A]rt thou come to destroy us? I know thee who thou art, the Holy One of God” (1:24). This spirit recognized Christ as God’s Holy One who will be His destroyer of demons. By recording this incident, Mark confronts his readers with Christ’s intermediary judicial role in the first chapter of his Gospel.
Mark 5:7 records that a demon addressed Christ as “Jesus, thou Son of the Most High God” and implored Him by God not to torment him. Both the demon’s address and his adjuring Jesus by God communicate the agency of Christ. The demon knew that Christ was the One who was uniquely related to the Most High God as His Son and distinct from Him. The demon’s plea to Christ shows that he understood that Christ is the Judge who will be the tormentor of demons. Mark also records that the demon “besought Him much that He would not to send them away out of the country” (5:10).
Luke’s parallel account states that the demons asked Christ not to command them to depart into the deep (8:31). Matthew’s version of this encounter says that there were two demon-possessed men (8:28) and multiple demons that addressed Him as the Son of God (8:29a). The demons also asked Him if He had come there ahead of the appointed time to torment them (8:29b). Their conversation with Christ testifies to their knowledge of an upcoming appointed time when Christ would indeed torment them.
All three Synoptic Gospels present Christ as God’s judicial executor through these accounts of the testimonies of demons. It is unclear to what extent the original participants and observers may have heard or understood what the demons said, but Christ’s silencing of the demons who spoke of His identity (Mark 1:25, 34) shows that He did not want their testimony about Him to be widely known. That being the case, it is noteworthy that all subsequent readers of the records of those accounts are given that information by the New Testament writers. Because of their inclusion in the Gospels, this facet of these accounts points to the importance of the testimony that they bear to Christ’s judging for God.
These testimonies also indicate the significance of that doctrine by referring to an appointed future time when Christ will destroy demons and punish them. These aspects of the judicial work of Christ show that His work as God’s judicial agent has a broader scope in terms of its subjects than does His work as Savior. Whereas He has judged and will judge both people and demons, He has not saved and will not save demons.
 Mark 1 was chosen as one of the base passages because it occurs earlier in the book than the parallel passage in Luke 4 does in that book. Mark 5 was chosen because it most directly presents Christ as God’s judicial agent. In addition, “exorcism is a prominent feature of Mark’s account of Jesus. He speaks of it as distinct from a more general healing ministry, and includes four individual accounts of exorcisms (1:23-27; 5:1-20; 7:24-30; 9:14-29), all of which are vividly related, and two of which include a dialogue between Jesus and the demon(s) which reveals their privileged knowledge of who he is.” R. T. France, The Gospel of Mark in NIGTC (Grand Rapids: Wm. B. Eerdmans Publishing Co., 2002), 100. Peter’s declaration, “God anointed Him [Jesus of Nazareth] with the Holy Ghost and with power: who went about doing good and healing all that were oppressed of the devil; for God was with Him” (Acts 10:38), confirms this assessment of Christ’s gracious judicial agency in casting out demons.
 In related teaching, the Gospel writers record that the Pharisees said that Christ cast out demons through the power of Satan (Matt. 12:22-29). Christ, knowing their thoughts, asserted that He was expelling demons by the Spirit of God and that His doing so showed that the kingdom of God had come on them (12:28). Both of those statements convey that Christ rendered God’s judgment in casting out demons.