8:31 Jesus' clear revelation of His coming suffering, death, and resurrection resulted from Peter's confession of faith. The disciples were now ready to receive what would have been completely incomprehensible if they still viewed Jesus as only a political Messiah.
Jesus referred to Himself as the Son of Man, a biblical messianic title (Dan. 7:13-14; cf. Mark 2:10, 28). This was by far the favorite term that Jesus used to describe Himself in the Gospels. It appears 81 times. In its Old Testament usage this title presented Messiah as coming in glory but also suffering and dying. This title was not as popular as "Messiah"so when Jesus used it people unfamiliar with the Old Testament often did not know what He meant.
Here Jesus revealed that the Son of Man must (Gr. dei) suffer. The popular idea was that Messiah would establish His kingdom without suffering and dying.
"The necessity arises, first, from the hostility of men; secondly, from the spiritual nature of his work, which made it impossible for him to oppose force to force; and thirdly from the providential purpose of God, who made the death of Jesus the central thing in redemption [Isa. 52:13-53:12]."207
The three groups that would reject Jesus constituted the Sanhedrin. The elders were its lay members. They were men of wealth and were the leaders of aristocratic families. The chief priests were the ranking priests and were mostly Sadducees. They occupied a hereditary office and supervised the temple and the sacrificial system. The chief priests included Annas, Caiaphas, and the leaders of the 24 divisions of the priesthood. The scribes or teachers of the law were the approved interpreters of the law, and they were mostly Pharisees. They were the theologians and lawyers of Judaism who were experts in Israel's laws. Together these three groups formed a united front as opponents of Jesus.
Jesus also announced His resurrection "after three days."Mark's readers would have understood this phrase as synonymous with "on the third day"(cf. Matt. 16:21; Luke 9:22).
"Verse 31 is particularly important because it is the only explanation in Mark's Gospel of the messianic secret.' Jesus did not want his messiahship to be disclosed because it involved suffering, rejection, and death. Popular expectations of messiahship would have hindered, if not prevented, the accomplishment of his divinely ordained (dei, must') messianic mission."208
8:32 Until now, Jesus had only hinted at His sufferings (cf. 2:20; 4:33-34; 7:14-15, 17-23). The disciples were unprepared for this clear revelation that Messiah would suffer, die, and rise again. Peter understood it but refused to accept it. He could not reconcile this view of Messiah with the popular one. The word Mark chose to describe Peter's rebuke is a strong one (Gr. epitimao). It is the same one he used to describe Jesus silencing demons (cf. 1:25; 3:12). Peter reacted with "an air of conscious superiority."209
8:33 Jesus spoke His rebuke for the other disciples as well as for Peter. This indicates that Peter was speaking for them. Jesus called Peter Satan because He recognized Satan as the ultimate source of Peter's suggestion (cf. Matt. 4:10). Peter's words had opposed God's will in favor of the popular messianic idea.