8:14 The disciples [as they traveled by boat from the western side of the Sea of Galilee to the eastern side] had forgotten to bring bread [from the scene of the last feeding (Mark 8:1-10): but had Jesus, the bread of life (Jn. 6:35) with them], except for one loaf they had with them in the boat.
8:15 “Be careful,” Jesus warned them [do not mix Christianity with the legalism of the Pharisees]. “Watch out for the [evil] yeast [or leaven, a permeating influence that affects the whole] of the Pharisees [i.e., a way of life filled with hypocrisy and legalism: cf. Luke 12:1] and that of Herod [i.e., a way of life characterized by worldliness: Mark 6:14-29].”
8:16 They discussed [argued] this with one another and said, “It is because we have no bread [the disciples apparently misunderstood Jesus’ warning].”
8:17 Aware of their discussion, Jesus asked them [therefore clarifying His point that His power and provision were sufficient to sustain them in their calling as disciples]: “Why are you talking about having no bread [the disciples failed to see Jesus as the bread]? Do you still not see or understand? Are your hearts hardened?
8:18 Do you have eyes but fail to see, and ears but fail to hear? And don’t you remember [what you recently witnessed that should have caused you to realize that your Master is sufficient for every emergency]?
8:19 When I [Jesus reminded the disciples of two occasions in which He had provided bread for thousands] broke the five loaves for the five thousand [see Mark 6:34-44], how many basketfuls of pieces did you pick up?” “Twelve,” they replied.
8:20 “And when I broke the seven loaves for the four thousand [see Mark 8:1-10], how many basketfuls of pieces did you pick up?” They answered, “Seven.”
8:21 He said to them, “Do you still not understand [that Jesus is the source of power for daily living and adequate to meet their needs]?”
8:27 Jesus and His disciples went on to the villages around Caesarea Philippi [near Mount Hermon at the source of the Jordan River; this was Gentile territory]. On the way he asked them [the most significant question people must answer], “Who [asking questions was one of Jesus’ favorite means of teaching] do people [popular opinion] say I am? [Jesus used this question as an opportunity to clarify His mission to His disciples]”
8:28 They replied, “Some say [see Matt. 14:1-2 and Mark 6:14] John the Baptist [whose ministry brought great spiritual renewal in Israel]; others say Elijah [Jews considered Elijah their most honored prophet; some believed Jesus was Elijah appearing in fulfillment of end-time prophecy as per Mal. 4:5]; and still others, one of the prophets. [popular opinion failed to recognize Jesus for who He really is]”
8:29 “But what about you [ultimately every person must decide for themselves the answer to this question]?” he asked. “Who do you say I am?” Peter [acting as a spokesman] answered [correctly; see Matt. 16:17], “You are the Christ [the Greek equivalent for the Hebrew word Messiah (one anointed by God); many Jews were expecting a military leader].”
8:30 Jesus warned [strong prohibition] them not to tell anyone about him [because any proclamation of Jesus as the Messiah could have led to conflict between the popular expectations of the people and the reality of what God was doing in Christ (W. Blackman); to avoid “messianic misunderstanding”].
8:31 He began to teach them [about the events He would encounter in the future] that the Son of Man [Jesus’ favorite designation of Himself: links Him with the Son of Man mentioned in the OT] must [Jesus’ death was a divine necessity — God’s plan for His life — He voluntarily laid down His life] suffer many things and be rejected [as a result of fulfilling His mission] by [all the key leaders] the elders [lay leaders; those who ruled the synagogues], chief priests [those in charge of temple worship — Sadducees] and teachers of the law [Pharisees — scribes], and that He must be killed [Jesus had an awareness of His destiny] and after three days rise again [see Mark 9:10; Jesus ultimate destiny was life, not death].
8:32 He spoke plainly [not indirectly as in the past] about this [His coming death], and Peter [who lacked a spiritual understanding of the Messiah’s suffering] took Him aside and [standing face to face] began to rebuke Him [this was an attempt to turn Jesus from His God-appointed mission of dying for the sins of the world, which is what Satan tried to do in Matt. 4:8-10; perhaps fearful that if there was a cross in Jesus’ future then a cross in theirs].
8:33 But when Jesus turned and looked at his disciples [who probably agreed with Peter], he rebuked Peter [for being Satan’s spokesman]. “Get behind me, Satan [Peter spoke the enemy’s mind; Jesus saw beyond Peter to Satan, the real source of opposition]!” he said. “You do not have in mind the things of God [Peter did not understand God’s purpose for Jesus], but the things of men [Peter was thinking like those around him].”
8:34 Then He called the crowd to Him [after private meeting with disciples] along with His disciples [for additional instruction about discipleship] and said: “If anyone would come after me, he must  deny [say no to and turning away from natural desires, ambitions, and pleasures] himself and  take up his cross [the cross was an instrument of death; an appeal for martyrdom; call to surrender everything dear; daily call to total commitment; see Gal. 2:20] and  follow me [by making a daily decision to honor Jesus in all our choices].
8:35 [restatement of the verse 34] For whoever wants to save his life [characterized by putting self first or at center of our decision-making] will lose it [including everything they amass and the approval of Jesus], but whoever loses his life [the world and its treasures] for me [act of devotion] and for the gospel will save it [enjoy eternal benefits].
8:36 What good is it for a man to gain the whole world [temporal things only enjoyed for a brief season], yet forfeit [an absolute loss; wasting your life; missing opportunities to make your life count] his soul [eternal welfare]? [better to gain your soul and lose the world]
8:37 Or what [possession; number one thing in your life] can a man give in exchange for his soul [refers to a person’s being]?
8:38 [Warning!] If anyone is ashamed [to take a stand for Jesus] of me and my words [fails to live daily as Jesus’ disciple] in this adulterous and sinful generation, the Son of Man will be ashamed of him when He comes in His Father’s glory with the holy angels.”