Luke briefly touches on a whole series of events about which the other evangelists, especially Matthew, speak in greater detail. He gives the central place to Peter's confession and to Jesus' account of His approaching death and resurrection. There is a logic to this presentation. First of all, the Savior lets His disciples feel the power of the Kingdom and learn from their own experience how this power acts in the world. And not only them: the miraculous feeding of thousands of people with five loaves and two fish is also possible only in the Kingdom. This is not surprising: when it comes to the Kingdom, it is easier to show than to tell. Meanwhile, even those who had previously taken no interest in Christ's testimony begin to notice it—for example, Herod, who was generally wary of every kind of messianic movement that threatened his power.
This is precisely why, immediately after Peter's confession, Jesus explains to the disciples just how different the messiahship He has brought into the world is. Of course, the apostles fully understood everything Jesus told them only on the day of Pentecost. But it was immediately after Peter's confession that He began speaking to them about His messiahship and His path. It is as though He is trying to make everything clear from the outset, so that His messianic ministry will not become associated in His disciples' minds with traditional popular messianic expectations.
From the very beginning, the Savior does everything possible to help His disciples understand as much as they can of what they will have to understand fully in due time. This is natural: Golgotha lay ahead. The disciples had to be prepared, as far as possible, for what awaited them—and what awaited them was the shock of the complete collapse of their entire worldview and sense of the world. Only the experience of the Kingdom could help them endure it—not the earthly kingdom of popular expectations, but the true Kingdom, the one the Savior brought into the world.
The apostles gained as much experience of the Kingdom as was then possible after they went out to preach on their own, without their Teacher. The new ideas about the Kingdom proved more difficult: they would not fit into the disciples' minds or find room in their consciousness. All that remained was to rely on their intuition and, above all, on the personal relationship that bound them to Jesus. Nevertheless, He tells the apostles everything that can be said in human words about His earthly path and earthly ministry. And then each one takes in as much of His words as he is able to take in.
