27 Jesus and his disciples headed out for the villages around Caesarea Philippi. As they walked, he asked, "Who do the people say I am?" 28 "Some say 'John the Baptizer,'" they said. "Others say 'Elijah.' Still others say 'one of the prophets.'" 29 He then asked, "And you - what are you saying about me? Who am I?" Peter gave the answer: "You are the Christ, the Messiah." 30 Jesus warned them to keep it quiet, not to breathe a word of it to anyone.
31 He then began explaining things to them: "It is necessary that the Son of Man proceed to an ordeal of suffering, be tried and found guilty by the elders, high priests, and religion scholars, be killed, and after three days rise up alive." 32 He said this simply and clearly so they couldn't miss it. 33 Turning and seeing his disciples wavering, wondering what to believe, Jesus confronted Peter. "Peter, get out of my way! Satan, get lost! You have no idea how God works."
Matthew Henry's Commentary on Mark 8:27-33
Commentary on Mark 8:27-33
(Read Mark 8:27-33)
These things are written, that we may believe that Jesus is the Christ, the Son of God. These miracles of our Lord assure us that he was not conquered, but a Conqueror. Now the disciples are convinced that Jesus is the Christ; they may bear to hear of his sufferings, of which Christ here begins to give them notice. He sees that amiss in what we say and do, of which we ourselves are not aware, and knows what manner of spirit we are of, when we ourselves do not. The wisdom of man is folly, when it pretends to limit the Divine counsels. Peter did not rightly understand the nature of Christ's kingdom.