31 And he began to teach them that the Son of man must suffer many things, and be rejected by the elders and the chief priests and the scribes, and be killed, and after three days rise again. 32 And he said this plainly. And Peter took him, and began to rebuke him. 33 But turning and seeing his disciples, he rebuked Peter, and said, "Get behind me, Satan! For you are not on the side of God, but of men."
Matthew Henry's Commentary on Mark 8:31-33
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.