27Now Jesus and His disciples went out to the towns of Caesarea Philippi; and on the road He asked His disciples, saying to them, "Who do men say that I am?"
28So they answered, "John the Baptist; but some say, Elijah; and others, one of the prophets."
29He said to them, "But who do you say that I am?"
Peter answered and said to Him, "You are the Christ."
30Then He strictly warned them that they should tell no one about Him.
Finally one of His disciples proclaims Jesus for who He is! Up until now, it was only demons who recognized Jesus. Jesus didn't allow the demons to tell anyone who he was. Jesus warned many who He healed to tell no one. And now that one of his disciples finally sees the light, He is still warning them to tell no one. Why?
Through His ministries so far, Jesus has been a great teacher and a great healer. Men have been waiting generations for the coming of Christ. They have seen many prophets come and go and have relished the news the prophets brought. He has referred to himself as Son of Man several times and mentioned that a prophet is never accepted in his own town. I can see how they would surmise that Jesus is another great prophet, someone coming to prepare the way for Christ -- the Christ that would save them and deliver them.
But the Christ they were expecting is far different from Jesus. I still think if people knew he was the Son of God, they might have tried doing something to prevent the eventual persecution and death that Jesus must go through. Also, if they knew Jesus was the Messiah they were expecting, they would have started preparing for the battle they wanted in order to overthrow the current rulers. So yes, we can rejoice that Peter finally proclaimed Jesus as the Christ. But He couldn't let that knowledge interfere with what He must do.
The other thing of interest to note here, is that Jesus has never tried telling anyone who He is. He is leaving it for everyone to decide for themselves. I think we too must decide for ourselves what Jesus is to us.