In the gospel of Mark, Jesus appears to have an obsessive interest in keeping his identity secret. The kinds of secrecy in Mark fall into roughly four categories.

1. On four separate occasions, Jesus orders the people he heals not to tell anyone about the miracle they just experienced.
   • Jesus heals a leper in 1:40-45, and then gives him a "stern warning" not to tell anyone what just happened. Oddly, he also tells him to show himself to the priest "and offer for your cleansing what Moses commanded, as a testimony to them." The leper explicitly disregards this command and promptly tells "everyone," forcing Jesus to flee the countryside so that he can avoid the crowds. (Luke parallels this story closely in 5:12-16; Matthew 8:2-4 keeps the command about the priest, but ends the narrative there.)
   • When Jairus' daughter dies and Jesus raises her in Mark 5:35-43, he "strictly" orders the girl's family not to tell anyone. The reader is not told whether they obey. Luke parallels the story closely in 8:49-56. Matthew tells a slightly different version of the story in 9:23-26, with no mention of secrecy.
   • When Jesus heals a deaf-mute in 7:31-37, he orders the man and his friends not to tell anyone, "but the more he ordered them, the more zealously they proclaimed it." This story does not appear in Matthew or Luke.
   • And finally, when Jesus heals a blind man at Bethsaida in Mark, he tells the man to go home without going into the village. Presumably this is so that he will not tell anyone in the village what happened, though neither the reason for the command nor the result of it is made clear in the gospel. This story does not appear in Matthew or Luke either.
2. In three exorcism scenes, Jesus tells the demons he exorcises to keep silent about his identity. One unusual feature of Mark is the theme that demons recognize Jesus as the Son of God long before human beings do. Jesus specifically orders the unclean spirit in 1:23-28 to be silent after it exclaims that Jesus is the Son of God. We are also told in passing in 1:34 and 3:11 that demons recognized Jesus, and that he had to command them not to talk about him.
3. When Jesus' disciples finally do understand the truth about Jesus' messiahship, he orders them to keep quiet about it.
   • Peter's declaration that Jesus is the Messiah in 8:29 is immediately followed by Jesus "sternly" commanding him not to tell anyone.
   • Similarly, when the disciples witness the Transfiguration of Jesus in 9:2-9, he orders them not to tell anyone what they have seen, then adds a new detail: until he rises from the dead. Matthew follows this story closely; Luke removes the command to keep quiet (but mentions that the disciples kept quiet anyway).
4. Finally, there is the strange discussion about parables that takes place in Mark 4:12. Jesus tells the disciples that he speaks in parables so that outsiders "may indeed look, but not perceive, and may indeed listen, but not understand; so that they may not turn again and be forgiven." The implications of this statement are so horrific (Jesus wants to exclude people from the possibility of forgiveness?) that Matthew tries desperately to soften the statement, implying in his version of the story that outsiders already "look but not perceive."

What do we make of all this? It seems even Matthew and Luke were somewhat embarrassed by Mark's obsession with secrecy; as I demonstrate above, the other synoptic gospels remove references to secrecy about half the time. Furthermore, Mark himself is not consistent about the secrecy theme, occasionally having Jesus perform miracles in front of crowds or hostile audiences. For example, he heals a man with a withered hand in 3:1-6 in the presence of his enemies, challenging the Pharisees verbally even as he does so.

The most common answer that Christians provide to this question has to do with Jesus' humility: he does not want to go around announcing that he is the Messiah or the Son of God, since that would be unbecoming. This does not remove all the awkwardness from the situation, however. Why does Mark's Jesus seem so exclusive and elitist, almost as if he is reluctant to heal people or exorcize demons? Being humble is one thing, but angrily shushing a follower and then going to hide in the countryside seems quite another, does it not?

At the beginning of the nineteenth century, a Biblical scholar by the name of Wilhelm Wrede wrote a book called The Messianic Secret which tried to provide an analysis of this difficult issue. Wrede believed that the secrecy theme was not original to Jesus, but rather that it was added to the gospel by Mark. Wrede's argument, which was and is still very influential in religious studies, goes something like this: Mark had to come up with a convincing explanation for why Jesus did not seem like a messiah during the course of his life -- remember that most Jews of the time were expecting a Messiah who was a king, a warlord, and a nationalist, and Jesus was none of those things. By emphasizing secrecy in his gospel, Mark could simultaneously claim that Jesus was the messiah and that nobody knew it until after he had died.

Wrede did not think that Jesus saw himself as the messiah. A lot of modern Biblical scholars (though by no means all of them) still agree with him, though his theory has been modified significantly over the course of the past century. Even Mark's own gospel portrays Jesus as being very evasive about his divine or messianic status, and in the other synoptics this is even more the case. The clearest image of Jesus' divinity comes out in the gospel of John, which is not very interested in secrecy at all.

Further Reading:

A very good summary of Wrede's hypothesis can be found here: http://atheism.about.com/od/biblegospelofmark/a/messianicsecret.htm

A criticism of Wrede can be found on this web page: http://www.tektonics.org/qt/secretmess.html