The demon's recognition and the exorcism demonstrate both Jesus' authority and its true source. Unlike a wonder worker, Jesus does not put his power on display to prove something about himself. Instead, he silences the demon Unlike the scribes or a personality cultist, Jesus does not derive his authority from other people, past or present. He possesses true authority -- the authority only God can give and exercise. The exorcism illustrates what the crowd has already noticed but not understood -- that as the preacher and teacher of the kingdom of God, Jesus is the bearer of the kingdom. In him, God's kingdom breaks in to destroy the power of every other authority, so "that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father" (Phil 2:9-11).
Mark's purpose in this text is to reveal Jesus' true authority in contrast to the misunderstanding of it. Though the people of Capernaum recognized Jesus as the kind of person who commanded respect, they still didn't recognize the true authority of Jesus. That is the point of the exorcism in vv. 23-26. Possessed by a power far greater than his own, the man with the unclean spirit recognized Jesus immediately. "He cried out… 'I know who you are, the Holy One of God'" (v.24). The demon recognized Jesus as the bearer of God's word. As the "Holy One of God," Jesus was the one in whom God exercised his power and dominion over the earth, speaking his word. Jesus spoke the word and drove the demon out. That is Jesus' true authority -- the authority of God himself, the authority of the one who makes all things new. Still the people of Capernaum didn't recognize it. Though they heard Jesus' word and the word of the demon, though they saw the demon cast out, they didn't know what to make of Jesus. They scratched their heads in wonder, assuming that it could only be some new kind of teaching (v.27). There is an epiphany in this story. As Jesus taught and drove out the demon with his word, he showed himself to the people, making his power manifest. But it is a secret epiphany -- the people didn't understand what they saw. The secret was kept until the cross and the resurrection and then revealed only to faith. That is how God manifests himself to us -- in hiddenness, by hiding his word in our words, by showing his power in weakness. Only faith can see such sights, and only faith can hear such a word. For the sight is given only to our ears. Authority is the key word in this text. As Mark uses the word authority in this text, authority means primarily power -- the power of God. Jesus' authority is in his word. As he speaks it, he not only tells us something but does something to us. Just as his word drove the demon out of the man with the unclean spirit, his word forgives us and gives us faith. It is his authoritative word, his powerful word, which creates life in the dead and liberates the possessed.