We lose focus so quickly!

And when they came to the crowd, a man came up to him and, kneeling before him, said, “Lord, have mercy on my son, for he is an epileptic and he suffers terribly. For often he falls into the fire, and often into the water. And I brought him to your disciples, and they could not heal him.” And Jesus answered, “O faithless and twisted generation, how long am I to be with you? How long am I to bear with you? Bring him here to me.” And Jesus rebuked the demon, and it came out of him, and the boy was healed instantly. Then the disciples came to Jesus privately and said, “Why could we not cast it out?” He said to them, “Because of your little faith. For truly, I say to you, if you have faith like a grain of mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move, and nothing will be impossible for you.”
As they were gathering in Galilee, Jesus said to them, “The Son of Man is about to be delivered into the hands of men, and they will kill him, and he will be raised on the third day.” And they were greatly distressed.
(Matthew 17:14-23 ESV)
Jesus had announced His upcoming "departure" - His death, burial and resurrection, and Peter and the others reacted against that, objecting that it should not happen.  They were stuck on the first two and totally overlooking the third.  This message was reinforced when they Key Three were allowed to witness the transfiguration and overhear Jesus, Moses and Elijah discuss the same departure. This was also misunderstood until they were overwhelmed by God's voice, cloud, and presentation of Christ and Christ alone.  Here, once again, they (and we) are challenged to consider how little faith we have, or more accurately, how little we truly believe that Christ can do anything - heal the sick, drive out demons, rise from the dead.  When Jesus repeats His earlier prediction, it is as if they had not been listening or learning anything since the first time. They were even more depressed, fearful, and confused.  Return to lesson one. Let us not be so short-minded and faithless! Let us put our minds on the resurrection accomplished and the promised one yet to come.