Chapter 9 is a bit of a fulcrum—a turning point—in Luke's Gospel account. One key verse is 51, when we're told that Jesus "set His face to go to Jerusalem". We'll take note of things leading up to that and the significance of that below, but for now the bigger picture is that Jesus is now moving away from His travelling ministry in Galilee (northern Israel) and towards Jerusalem. Luke gives us a much longer "journey to Jerusalem" narrative than the other Synoptic Gospel accounts (one chapter each in Matthew and Mark). In Luke's account, there are 10 chapters devoted to this journey, beginning at 9:51.
A few notes on the text:
9:1-6, 10-11 Authority, Preaching, Healing
Jesus gives The Twelve (a bit of a technical term, which is why we capitalize it here) authority to preach and to bring the Kingdom by means of healing and driving out demons. These are the same things that Jesus Himself has been doing in the previous chapters (e.g. 4:31-32,5:17, 6:18, 8:1). The implication of course is that the authority to do these things in fact belongs to Jesus (remember 4:32), and not only the right to bestow it, but also the ability to bestow it, is His also.
9:7-9 The Interest of Herod
The word "tetrarch" comes from Greek "tetra" (four) and "arché" (head/ruler). This Herod was not a king but a ruler of a fourth of the kingdom, along with three of his brothers, sons of Herod the Great. He is the one who had John the Baptist beheaded (chapter 3), and so his confusion stems from wondering who this man is who's doing signs and wonders. Notice the descriptions given about who people are saying Jesus might be; we'll see it connect a few verses later in Peter's confession of Jesus.
9:10-17 Feeding (far more than) Five Thousand
Reading the accounts of this miraculous feeding carefully, in all the Gospel accounts in which it appears, leads us to note that the number 5000 is only the men (9:14).
Also notable, other than the miracle itself, is the undertones of the Lord's Supper. That had not yet been instituted, but for those familiar with it (and our practice of Holy Commmunion) will hear significant connections between what we know as the Words of Institution and what Jesus does here: he takes the food (in this case, not only bread but also fish—but far, far too little for so many people), blesses it/gives thanks, breaks it, and gives it to the disciples. This is a supernatural meal in much the same way as the Lord's Supper is!
9:18-20 Jesus is the Christ
Though Luke's account is more brief than Matthew's, Peter confessing Jesus to be the Christ—the Messiah, the Anointed One—of God is the core of it.
9:21 The Messianic Secret
We often hear this in the Gospel accounts; it's maybe most prominent in Mark, but Luke emphasizes it as well: Jesus desires that this confession of Him as Christ is not yet ready to be widely proclaimed. It's only after His death and resurrection that He commissions the Church to spreading this information and news to the world. We often wonder why the timing is like that, and the best answer we can give is that it was God's will; the specific reasoning is never explicitly mentioned.
9:22 The Plan Revealed
This is the first time in Luke's account that Jesus tells anyone what God's plan is. Remember, there is this theme of "it is necessary" in Luke's account, and we see it again here. The little Greek word "deî" appears again: "it is necessary that the Son of Man must suffer…be killed, and on the third day be raised".
9:23-27 Following Jesus
This might not strike us as odd, because we're most likely reading with the whole story already in mind. But step into the world of the disciples for a moment: Jesus has just predicted His death, and then says that anyone who wants to come after (follow) Him must "take up his cross daily". Jesus hasn't died on a cross at this point, so it could be understandable that the disciples may not grasp the full picture. But with these words, Jesus is telling them in what way He will die, and that—even in a metaphorical way—following Him is very much the way of the cross, not the way of ease and comfort. (The word "daily" gives us the clue that Jesus isn't speaking only literally here; literally following Jesus to the cross would be a one-time event, and for some disciples that's exactly what happened. But all of His followers are to live the way of the cross—self-sacrifice for others—daily.)
9:28-36 The Transfiguration
We dealt with this passage in more detail during worship on Transfiguration Sunday. The changing of Jesus' appearance to reveal His glory is an amazing thing, as is the appearance of Moses and Elijah speaking with Him about His departure (literally, His "exodus") which was about to be fulfilled (fulfillment is again a sign of the plan - the plan has to be fulfilled) at Jerusalem, where Jesus will be beginning to go very shortly.
9:37-50 Another Glimpse of the Kingdom and the Disciples Continue to Struggle
Jesus again heals someone from demonic possession and foretells His death, and the crowds and His disciples are continuing to have trouble understanding the true nature of Jesus' power, ability, and calling as well as their own. An interesting note on 9:45 is that there seems to be a use of the "divine passive" here, where the passive voice in grammar is used (see what we did there?) to indicate that God is the subject of the action. So "it was concealed from them" implies that God is the one doing the concealing. Again, we hear of this Messianic secret.
9:51 The Linchpin Verse
A short verse, but a truly critical one. Again we hear of the plan: "the days drew near"—Luke again uses the Greek word for "fulfill" here—and a reference to His being "taken up" (again, His departure, which is best understood as not just the ascension, but the whole of the suffering, death, resurrection, and ascension). As these days were about to be fulfilled, Jesus "set His face" towards His journey to Jerusalem, knowing that He was going there to suffer and die. This is a most wonderful phrase, that Jesus "set His face". It's the sense of being resolute, of being established and strengthened in a cause, being committed to it. Of course, it was not just His face, but His whole presence; the idea of "turning one's face" on something is a Hebrew way of talking about presence and favour. Remember our benediction in worship? For God to "shine His face upon us" and to "look upon us with favour" is for Him to show us His grace and mercy. That's the primary goal that Jesus has, knowing that's the result of Him going to Jerusalem: salvation for the whole world.
9:57-61 Following Jesus to Jerusalem
We may think of this as rather harsh of Jesus. But consider the context and the important verse 51 that we've just heard: Jesus has "set His face" and they're on the road to Jerusalem. The one who wants to avoid the way of the cross is one who wants to put other things before Jesus. (Remember back to 9:23-24). Those that are speaking to Jesus at this point are committing to follow Him wherever He goes, not understanding that where He's going right at that moment is to suffer and die.