Charles Ellicott Commentary Matthew 16:21

"From that time began Jesus to show unto his disciples, that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and the third day be raised up." — Matthew 16:21 (ASV)

From that time forth began Jesus—The emphasis placed on this prediction shows that it struck the disciples as something entirely new.

They had failed to understand the mysterious hints of the future found in His words: in “Destroy this temple” (John 2:19), in the Son of Man being “lifted up” (John 3:14), and in the sign of the prophet Jonas (Matthew 12:39; Matthew 16:4).

Now the veil is lifted, and the sequence of events is plainly foretold: the entry into Jerusalem, the rejection, the condemnation, the death, and the resurrection.

Clearly, if we accept the record as true, the prediction implies a foreknowledge that is, at minimum, supernatural. This serves as evidence of a divine mission, and perhaps even of a divine nature in the speaker.

It can also be argued that the events surrounding the prediction—e.g., Peter’s protest and the rebuke addressed to him, which stand in such striking contrast to the previous promise—are so original and unexpected that they refute the theory of this being a prophecy written after the event.

On the other hand, the fact that the disciples did not grasp the meaning of the prediction about His rising from the dead can, in turn, be used to argue against the assumption that the prophecy lingered in people’s minds and led to the belief in a mythical fulfillment in the absence of a real one.