In the Gospel of Mark, Jesus often tells people not to reveal his true identity as the Messiah (God's chosen one). This includes:
those Jesus healed or raised from the dead,
the disciples who knew Jesus was the Christ (the Greek word for Messiah), and
the demons who understood Jesus' true identity (see Mark 1:34, 44; 3:11–12; 5:43; 7:36; 8:29–30; 9:9).
This theme (often called the "Messianic Secret") appears less often in the Gospels of Matthew and Luke (see Matthew 8:4; 16:20; Luke 9:21). Why did Jesus command those he healed and those who knew his true identity to keep both his healing miracles and his identity a secret?
One possibility relates to how the Roman authorities would have reacted. During his earthly ministry, Jesus was a very popular preacher who announced the arrival of God's kingdom. He miraculously healed people and allowed his followers to call him Israel's long-awaited Messiah and King.
Roman authorities would not allow this. They would quickly try to stop such a movement. In the Roman Empire, there was no room for another kingdom or messianic rescuer within Roman rule. Therefore, even though Jesus told his disciples he was the Christ, he did not plan to lead a political revolution against Rome (Mark 8:27–30).
Another reason Jesus might have wanted to keep his true identity secret might be the widely misunderstood identity of Jesus in the Gospel of Mark. There was a misunderstanding even among his closest followers. Jesus makes it clear that his role as Messiah, the Son of God, is directly related to his suffering and death. This reality did not match Jewish expectations of the Messiah.
Right after the apostle Peter declares Jesus as the Christ (the Messiah), Jesus announces he will suffer and die (Mark 8:27–31). Peter's response shows he does not understand (8:32–33). Jesus' miracles and deep teaching were important, but his death as a sacrifice was the most important part of his role as the Messiah.
For these reasons, Jesus found it wise to teach about God’s kingdom using parables. Parables are stories that have symbolic meanings (see Mark 4:1–34, especially 4:10–12). This approach helped reduce the excitement caused by his miracles (1:44; 5:43; 7:36; 8:26). It also allowed him to hide his presence at times from the people (7:24; 9:30–31). He kept his teachings hidden from outsiders (4:10–12, 33–34; 7:17). He instructed those who knew his true identity not to reveal it (Mark 1:23–26, 34; 3:11–12; 8:29–30; 9:9). Jesus came “to give his life as a ransom for many” (10:45). He did not come to lead the nation of Israel in a rebellion against Rome.
But Jesus Christ, the Son of God, could not be hidden (Mark 1:1). The secret was impossible to keep because Jesus is too important (7:36). Those who experienced his healing and saw him heal others could not stop sharing what he did. Jesus's identity became clear, and people realized he is truly the Messiah, the Son of God, the one with power over nature, sickness, and death. For readers and hearers of the Gospel of Mark who learn of his identity in the first verse, Jesus proved to be the Messiah because of (not in spite of) his suffering, death, and resurrection.
Passages for Further Study
Matthew 8:4; 16:20; Mark 1:34, 44; 3:11–12; 5:43; 7:36; 8:29–30; 9:9, 30–31; Luke 9:21