The passage
      v21. Jesus had already alluded to his coming death, but now he openly "explains" it to the disciples. In speaking of his suffering, he uses the word "must". This is the Father's will and it "must" be accomplished.
      v22. Peter strenuously rejects the idea of a suffering messiah. Peter has a big heart, but also a big mouth.
      v23. Jesus turns, faces Peter, and rebukes him strongly. The words and actions of Jesus are obviously very striking and were well remembered. First, he compares Peter's words with Satan's temptation of a kingdom gained without suffering. The possibility of another way, rather than the "cup" of suffering, is always before Jesus. Second, Peter, who was just described as the "fortress rock" (the believing man) upon whom Christ will build his church, is now described as a rock of stumbling, a rock to trip Christ up. Third, Peter, who had just declared a truth revealed by the Father, is now identified as a source of mere human thoughts, and corrupt at that.
      v24. Crucifixion was a common event in Palestine, as was the sight of a person carrying part of their cross to the place of execution. To "take up one's cross" powerfully images renunciation of self - death to self. Although these words are directed to the disciples, they are for "anyone". Yet, are they "a prerequisite of discipleship to Jesus", or a "continuing characteristic of it"? Many believers do argue that cross-bearing is a prerequisite for a personal relationship with Jesus. The problem with such an interpretation is that cross-bearing (in the terms of disowning personal human rights for a greater spiritual good) is not always an observable characteristic of a disciple. It is more likely that the renunciation that Jesus speaks of here involves an embarrassing surrender (commitment, faith in) to a suffering messiah. If we wish to follow Jesus to glory and stand with him there, then we will have to set aside all dependence on self (including grandiose expectations of a glorious messiah), and rely on the crucified one alone.
      v25-26. If we, in the power of our own will, seek to preserve our self-being, our personal independent eternal self, then we will lose everything. Only by surrendering ourselves to the dying and rising Christ, by losing ourselves in him, can we find and preserve our eternal being, our "soul", our "life". Even possessing the whole world cannot compensate for the loss of our soul.
      v27. In the day of judgment, we will be rewarded on the basis of what we have done. In the context, the deed is our surrender to Christ. If we rest in faith on the cross of Christ, then we will be saved. Some argue that the deed is cross-bearing discipleship, in the sense of an exemplary Christian life, but this would leave us with a doctrine of salvation by works.
      v28. This verse has many possible interpretations. Most commentators take "will not taste death" to mean "will not die", but a metaphorical sense is best, "will not face eternal annihilation." Those who opt for "will not die" tend to think that Jesus' words apply to the destruction of Jerusalem in 70AD. Certainly, some of those standing there that day, did see this terrible event. Yet, it is more likely that Jesus is saying that some in the crowd, a small band who have put their trust in him, will share eternity with him. They will be part of that throng without number, who come with the Son of Man into the presence of the Ancient of Days to receive glory, power and might.

True identity
      It is very common for us to find identity, meaning, personhood,.... the substance of our being, in the things we own, our job, our personal abilities.... Often the car we drive serves to define our character, or at least, defines it the way we want others to see it. Our home, furniture and boys-toys can be used in the same way.
      Of course, we know only too well, "it's all going to burn one day". Getting ourselves overly fussed with the accumulated debris of this world is the height of foolishness. What gain is there in possessing all the world only to inevitably find that someone else gets to clean out our drawers and carry off all our gear. The real prize surely has to be an integral personhood, a "life", a "soul" that is eternal. Identity in our car, home, kids... is fleeting. Identity in Jesus, in the crucified and risen one, is eternal. Our true self, our eternal self, is only found in him. It is found in all that he has freely done for us.
      We can't live without "gear", without toys and all the clutter of survival, along with our dreams and aspirations, yet we don't have to surrender to them. To surrender is to die, but to surrender to Christ is life eternal. "What benefit is there to anyone if they gain the whole world but forfeit their own life?"

v22
      proslabomenoV (proslambanomai) aor. mid. part. "took [him] aside" - having taken him, gathered to / brought along with. The participle is probably temporal, "then" Peter ...." "Took hold of", REB, is possible, but the sense is probably of Peter taking Jesus to one side to correct him privately. Another insight into Peter's very human character.
      iJlewV soi "never, Lord!" - God be gracious to you. As an exclamation "perish the thought!", "preposterous!". Used with a personal pronoun, second person "you" = "mercy toward you." Often with God stated or understood, "may God be merciful toward you rather than leaving you to face this circumstance alone." So, "God forbid!" which is what Peter is probably saying.
      ou mh "never [happen to you]" - Double negative expressing an emphatic denial that Jesus could be rejected.

v23
      uJpage opisw "get behind [me]" - go/depart behind. Usually in the sense of "go", so a forceful, "get out of my sight", but possibly "get behind me", ie. "become my follower again", Barclay.
      satana "Satan!" - A very strong address. Peter is taking the role of Satan by tempting Jesus.
      skandalon (on) "stumbling block" - a cause of offence, or more particularly a prompt to sin, "a trap". Peter is setting a dangerous trap for Jesus, similar to the one Jesus faced in the wilderness. The only way for Jesus is the way of suffering and death. "Your doing your best to trip me up", Barclay.

v24
      tote adv. "then" - "next in sequence", Morris. Note how Mark, expanding on this section, states "and having called together the crowd along with his disciples, said to them..." It is of particular interest that Mark makes the point that these words are for the "crowd" as well as "the disciples." Matthew's use of "if anyone would come after me" (Mark has "follow") further indicates that these words are not simply an encouragement for disciples to upgrade their discipleship to the "cross-bearing level, but rather a call for commitment to Christ.
      ei + ind. "if" - expressing a hypothetical case, not doubt. Conditional sentence, 1st class.
      qelei (qelw) "would" - wills [to come]. Expressing a decision of the will.
      aparnhsasqw (aparneomai) aor. mid. imp. "deny [himself]" - let him give up his own rights, renounce, pay no attention to, reject. The aorist points to a single act of renouncing self interest, possibly a strong aorist, "deny utterly." Commentators will often treat "deny" in terms of discipleship, eg. expressing the need for a disciple to "concentrate on meeting the needs of others rather than promoting ourselves", Morris. Yet, this is a word for "anyone", not just disciples. The word is used of Peter's denial of Jesus, of "disowning" or "disclaiming" him. The positive sense of "surrender" ("obedience to" the divine will, Davies and Allison) probably best illustrates the sense here. What we have here is a call for commitment to Christ, as against a commitment to our own self interest, "leave self behind", NEB.
      aratw (airw) aor. imp. "take up [his cross]" - take up, lift up, carry off [the cross of him]. Again an aorist, a singular action of picking up rather than carrying, expressing a "deliberate dying to oneself", Hagner. The cross-bearing image obviously illustrates the nature of denial, a denial Jesus himself undertakes in his own death (his surrender/obedience to the will of the Father). Verse 27, although bearing some similarities, is quite different to Mark's record of Jesus' words. Mark has Jesus warning his listeners that on his return he will be ashamed of those who are ashamed of him and his words, while Matthew has Jesus warn that on his return he will "repay everyone for what has been done." Surrender to the divine-will in Christ is the counter to being ashamed of him, not cross-bearing discipleship. The deed that diverts judgment is similarly surrender to Christ, not cross-bearing discipleship. So, the image of taking up the cross, of a deliberate dying to oneself, illustrates "surrender" rather than "service", a surrender to the divine call to believe for salvation in Jesus, a crucified messiah.
      akolouqeitw (akalouqew) pres. imp. "follow" - The present tense indicates the ongoing action of discipleship, probably reflected in Luke's difficult phrase "take up his cross daily."

v25
      ean + subj. Introducing a conditional clause, third class, with a future tense in the apodosis, expressing what will occur if.
      qelh/ (qelw) subj. "wants" - wills. Again an action of the will is indicated. "Whoever desires to save his life", Weymouth.
      yuchn (h) "[save his] life" - Is this a reference to the "soul", or life, in the sense of "ones true being", or to "the sum of physical existence here and now"? Those who lean toward a "discipleship" interpretation of this passage understand "save his life" in terms of "those persons who try selfishly to guard their existence (and so) will not know the full commitment of discipleship and will tragically end up losing the very thing they tried to protect", Hagner. If the passage is approached literally in the terms of martyrdom, then the person who wills to lose his life has to be widened to include the person who "is prepared to lose his life", Barclay (a rather blatant sidestep). Calvin suggests "life" means "soul" here, a person's eternal being. Our eternal being is lost to us if we "abandon Jesus and his messianic pathway", Hill, but is gained if we "surrender" to him. Life eternal is ours when we believe in the crucified messiah, even though such belief may be embarrassing ("ashamed of me").
      apolesh/ (apollumi) aor. subj. "lose" - "Considers his own life as unimportant in order to become my disciple", TH.

v26
      wfelhqhsetai (wfelew) fut. pas. "what good will it be" - what profit, benefit. "Will a person gain anything if ...", TEV.
      kerdhsh (kerdainw) aor. subj. "gains" - he should gain, profit. "Gain" in the sense of possess all that the world has to offer.
      zhmiwqh/ (zhmiow) aor. pas. subj. "forfeits" - loses, to have confiscated. "If you want to save your life you will destroy it", CEV.
      yuchV (h) "soul" - There are numerous renderings of "soul" here, but it seems best to see it as a parallel meaning to "life" in v25. "What could a man (person) offer to buy back his (their) soul ("one's true/essential being") once he has (they have) lost it?", Phillips.
      antallagma (a) "in exchange" - something given in exchange. Possibly: "as compensation."

v27
      mellei (mellw) "is going" - is about to [come]. Used of divine decrees "is destined / must / will certainly", BAGD.
      ercesqai (ercomai) inf. "to come" - Complementary infinitive, completing the sense of the verb "is about." The coming of the Son of Man is a technical descriptive that causes no end of trouble in the interpretation department. In the first place, Daniel's coming Son of Man is a coming to the Ancient of Days, ie. a coming to heaven, not earth. Yet, although Daniel's coming, 7:13, is a "coming with the clouds", not angels, in Matthew 25:31, we have a coming with angels, in glory, where the Son of Man "will sit on his throne in heavenly glory", and the nations gathered before him and the people separated one from another. So, is this the sense of the coming here, or is this coming a coming to "the world", a coming of the Son of Man, with his angels, for the final harvest, eg. the parable of the weeds, 13:24-30, cf. 13:49? Even the parable of the weeds has it's problems, since evil is weeded out of the kingdom, not the world, 13:41. See below.
      en th/ doxh/ tou patroV "in the Father's glory" - in the glory of the Father. "In the Father's splendor"
      meta twn annelwn autou "with his angels" - In the great separation of the just from the unjust, the angels are the instruments of the Son of Man's judgment of humanity. Daniel clearly draws a distinction between "the angels" and "the saints", but in the New Testament we are sometimes left wondering if the angels (messengers of God) aren't actually the saints.
      apodwsei (apodidwmi) fut. "reward" - he will recompense, give back, repay. A payment of what is exactly due, so used of wages etc. "He will settle accounts with each man", Barclay
      praxin (iV ewV) sing. "done" - something carried out, performed, deed. If a collective sense is indicated then "the sum of their conduct", but we are possibly looking at a single deed. In the context this means faith in Christ. "He will give everyone his due reward", REB.