What does Mark 1:25 Mean?
One of the miracles Jesus performs to authenticate His message is knowing what He could not, by natural means, know (John 4:28–30). Demons also know truths about the spiritual world that they sometimes communicate to people (Mark 5:7; Acts 16:16–17). But God does not want us to interact with demons, even to learn more about Him. Jesus is divine, as the spirit had noted (Mark 1:24), however, Jesus has His own plan regarding how and when to reveal Himself to humanity.
To keep the evil spirit from interfering, Jesus gives the demon two commands. First, he is to "be silent," or literally "muzzled." This is from the Greek root phimoo, used for the instrument used to keep an animal from opening its mouth. Similarly, when faced with demonic influences, our first act should be shutting our ears; Jesus does not want us to listen to them.
Second, Jesus commands the spirit to leave the person he is controlling. In that time, self-labeled exorcists used magical formulas or rituals in an attempt to remove unclean spirits. Jesus simply commands the spirit to leave. This act reveals His unique and ultimate power over evil. However, it also shows His submission to God.
Jesus could have banished Satan during the temptation in the wilderness (Matthew 4:1–11), but the temptation was essential to establish Jesus' identity as the sinless sacrifice. This act also shows a contrast with His time on the cross. Though Jesus could have stopped the crucifixion, He chose to endure the will of the Father in order to complete the plan of God. His plan was to provide the opportunity for salvation for all people through His atoning sacrifice for sin (John 3:16).
Source: www.bibleref.com