"The Great Confession" 

The key lesson in this chapter is Peter's confession of faith, we must consider the entire chapter to get the proper setting. Keep in mind that Christ and His disciples have been in "retirement" and He has been preparing them for His approaching suffering and death. Peter's confession of faith at this point is the climax of the months of retirement. From that point on, Christ openly teaches them about His crucifixion, and they began to make their way to Jerusalem.
I feel there are four outstanding movements here:
CONFLICT (1-5) CONFUSION (6-12) CONFESSION (13-20), and 
CORRECTION (21-28)

1. CONFLICT -- Christ tempted by the enemy -- 16:1-5
   Notice how the Pharisees and Sadducees, who were enemies, united to tempt Christ. Pilate and Herod were "made friends" for the same reason (Luke 23: 6-12). In asking for a sign "from heaven" they were discrediting His miracles. Perhaps they wanted fire from heaven, as Elijah had done; or bread from heaven, as Moses had done.
   Jesus describes their spiritual condition: (1) they could interpret things physical and worldly, but not things spiritual; (2) they were wicked, in that they tempted God; and (3) they were adulterous in that they had forsaken the true God for their empty religion. They were like some religious people of today. He points again to His death, burial, and resurrection, and to His ministry to the Gentiles, by referring to the prophet Jonah.
2. CONFUSION -- "The unbelief of the Disciples." 16: 6-12
   The disciples were apparently more concerned about physical things than spiritual; for while Christ was considering the sad state of the Pharisees, the disciples were irritated because they had forgotten to bring bread with them. The seven baskets left over from the feeding of the 4000 (Matt. 15:37) were probably given to the poor. When Jesus spoke of spiritual things - the leaven of the Pharisees and Sadducees -- the disciples thought only of physical bread. This is an illustration of Matthew 13: 22 -- the cares of this world choking out the seed of the world. Christ rebukes them for their "little faith"; for if they needed bread, could they not trust Him to provide it. He had just fed 4000 people with a few loaves and fishes.
3. CONFESSION -- Peter's confession of the Christ -- 16:13-20
   How confused the multitudes were about Christ ! They held him in high esteem, ranking Him with the great prophets; but they lacked the perception to see Him as the very Son of the living God. They even compared Him with John the Baptist. No man can confess Christ apart from the revelation of the Father (Matt. 11: 27) and the witness of the Spirit (1 Cor. 12:3). A right confession about Christ is important to salvation (1 John 5:10; 1 John 2:22-23; and John 20:31).

4. CORRECTION -- Peter the stumbling stone -- 16:21-28
   Christ now openly announces His coming suffering and death. He had intimated His death in various symbols in John 2:19, 3:14, 6:51, and Matthew 9:15 and 12:40-41; but now He spoke of it openly (Mark 8:32). The disciples were shocked at the news, especially Peter, who repeated Satan's temptation of Matthew 4:8-10 by trying to detour Christ from the cross. Satan was obviously using Peter again to hinder Christ's work (Luke 22:31). Christ rebuked Peter and then taught the disciple the importance of the cross in the life of the believer. "Bearing the cross" means dying to self, bearing Christ's reproach, crucifying the world and the flesh as we follow Him in obedience. Peter was to learn that suffering and glory always go together (1 Peter 4:12-19; 5:1 and 10).

• THE ROCK is Jesus Christ. Christ said so (Matt. 21:42) quoting Isa. 28:16. Peter himself said so (1 Peter 2:4-8 and Acts 4:11-12 with Psalm 118:22). Paul names Christ as the Rock in (1 Cor. 10:4, and repeatedly calls Christ the Head of the Church (Eph. 1:20-23, Eph. 4:8-16; Eph. 5:23, Col. 1:18). Throughout the OT, the Rock is a symbol of God, not man (Deut. 32:4, 15; Dan. 4:37; Psalm 18:2).
  Read also 1 Cor. 3:11.
• THE KEYS -- refer to Peter's stewardship in the kingdom.
  These are not the keys to the church, but the kingdom; and not to death or eternity, for Christ holds those (Rev. 1:18). Keys in the Bible stand for authority and stewardship ( Isa. 22:15, 22; Luke 11:52). Peter used these keys when he "opened the door of faith" (Acts 14:27) to the Jews (Acts 2), the Samaritans (Acts 8), and the Gentiles (Acts 10)
  This is stewardship not lordship.
• BINDING and LOOSING implies applying God's Word to men.
  In 18: 18 this is used of church discipline, and the power is given to ALL the disciples, not Peter alone. In Jesus' day the Jews spoke of "binding and loosing" when a rabbi would forbid something or permit something to be done. Read 1 Peter 5:1-4. Notice that it is Christ that builds the church.

1. Eph 2:20 is sometimes used to "prove" that Peter was the foundation rock of the church. If so, then the other apostles, and the NT prophets must be included ! "The foundation of the apostles and prophets" does not mean the foundation COMPOSED OF the apostles and prophets; but rather, the foundation which they laid through ministries, namely, Jesus Christ (1 Cor. 3:11)
2. To the unbelieving Jews, Christ is a stone of stumbling (Rom. 9:32
   To the Gentile nation, He will be the sitting stone of Daniel 2:34. To the lost, He is the crushing stone of Matthew 21:44. To the Church, He is the foundation and chief corner-stone (1 Cor. 3:11; Eph. 2:20). He will some day be the chosen stone of Israel's earthly kingdom (Isa. 28:16).