Mark 1:25-28

 Jesus has been given all authority in heaven and earth. He is God. Everything is under His command. Everything is under His control. Now He accomplishes this through the power of Holy Spirit until He comes again in glory to rule. His Kingdom  has no end!

Hebrews 11:1 says, "Now faith is the assurance of things hoped for, the conviction of things not seen." 

We live by faith when we trust God's promises are true, even when our circumstances remain unchanged. We live by faith when we trust that Jesus secured our relationship with God, even when we're tempted to try to earn God's favor with good works. We live by faith when we believe Jesus will return and consummate His victory in the new heavens and new earth, even when it seems that this world is deteriorating before our eyes. First5 

Mark 1:25-28

25 But Jesus rebuked him, saying,  “Be quiet, and come out of him!” 26 And when the unclean spirit had convulsed him and cried out with a loud voice, he came out of him. 27 Then they were all amazed, so that they questioned among themselves, saying, “What is this? What new doctrine is this? For with authority He commands even the unclean spirits, and they obey Him.” 28 And immediately His fame spread throughout all the region around Galilee. The New King James Version

The demon cried out let us alone, not because it was speaking for other demons in the man but because Jesus was a threat to all demons. Jesus constantly confronted demons and about 20 percent of the approximately 35 miracles recorded about Jesus involved helping those troubled by demons. The demon acknowledged Jesus as the Holy One of God, but Jesus refused the testimony from such a disreputable source. 

Mark notes the extent of recognition this great miracle brought Jesus by saying His fame spread throughout all the region. Mark creates suspense by contrasting the people who received Christ with the Pharisees and rulers who worked to bring about His death. The sad truth remains that often the religious of the world do more to keep people from Jesus Christ than most worldly atheists. But the gospel is not religion. It is Good News that can free even the most horrible sinner. The NKJV Study Bible

With this command, Jesus simultaneously neutralizes the spirit’s attempt to oppose Him and prevents His identity as the Messiah from becoming public knowledge. Exorcists were common in the ancient Near East. For example, among the Dead Sea Scrolls (circa 250 bc–ad 50), a text containing an incantation formula designed to exorcise demons was discovered. Jesus distinguishes Himself from other exorcists in that He did not rely on complex incantations. He could simply command the demons and they would leave their hosts. Jesus’ inaugural exorcism sets off a chain reaction, as those who hear the good news respond to it. Faithlife Study Bible

This unclean spirit hated and dreaded Christ, because he knew him to be a Holy One; for the carnal mind is enmity against God, especially against his holiness. When Christ by his grace delivers souls out of the hands of Satan, it is not without tumult in the soul; for that spiteful enemy will disquiet those whom he cannot destroy. This put all who saw it upon considering, What is this new doctrine? A work as great often is wrought now, yet men treat it with contempt and neglect. If this were not so, the conversion of a notorious wicked man to a sober, righteous, and godly life, by the preaching of a crucified Saviour, would cause many to ask, What doctrine is this? Matthew Henry’s Concise Commentary

Matthew 4:24 Then His fame went throughout all Syria; and they brought to Him all sick people who were afflicted with various diseases and torments, and those who were demon-possessed, epileptics, and paralytics; and He healed them.

Matthew 9:31 But when they had departed, they spread the news about Him in all that country.

Matthew 17:22 Now while they were staying in Galilee, Jesus said to them, “The Son of Man is about to be betrayed into the hands of men,

Mark 8:11 Then the Pharisees came out and began to dispute with Him, seeking from Him a sign from heaven, testing Him.