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.