From that time forth began Jesus to show unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day.
All Commentaries on Matthew 16:21 Go To Matthew 16
John Chrysostom
AD 407
Peter was examining the issue by human and earthly reasoning. He thought it disgraceful to Jesus as something unworthy of him. Jesus responded sharply, in effect saying, “My suffering is not an unseemly matter. You are making this judgment with a carnal mind. If you had listened to my teachings in a godly way, tearing yourself away from carnal understanding, you would know that this of all things most becomes me. You seem to suppose that to suffer is unworthy of me. But I say to you that for me not to suffer is of the devil’s mind.” So he repressed Peter’s alarm by contrary arguments. Remember that John, accounting it unworthy of Christ to be baptized by him, was persuaded by Christ to baptize him, saying, “Let it be so now.” So we find Peter as well, forbidding Christ to wash his feet. He is met by the words, “If I do not wash you, you have no part in me.” Here too Jesus restrained him by the mention of the opposite, and by the severity of the reproof he repressed his fear of suffering. The Gospel of Matthew, Homily