Jesus And The Disciples Descend From The Mountain. The Truth About John the Baptist (17:9-13).
As they were coming down from the mountain Jesus commanded silence about what they had seen until He had risen from the dead. (They would be unaware of how soon that would be). It was not only the idea of His Messiahship that He did not want spreading (by those who did not fully understand it), it was the whole idea of Who He really was, to those who were not ready to receive it.
However they were now totally confident that He was the Coming One, and that the ‘last days' were here. But in view of this they could not understand why Elijah had come and gone. They were puzzled. It was clear from what they had seen that the work of Moses and Elisha was now completed. Why then did the Scribes teach that Elijah would first come preparatory for God to act? Jesus' reply was clear and simple. Elijah had come. He had come in the person of John the Baptist (compare Luke 1:15-22). But He incorporated within His reply a further warning of His coming suffering. They must not be deceived by having seen His glory into thinking that He could therefore not suffer.
Analysis.
a As they were coming down from the mountain, Jesus commanded them, saying (Matthew 17:9 a).
b “Tell the vision to no man, until the Son of man be risen from the dead” (Matthew 17:9 b).
c And his disciples asked him, saying, “Why then do the scribes say that Elijah must first come?” (Matthew 17:10).
d And he answered and said, “Elijah is indeed coming, and will restore all things” (Matthew 17:11).
c “But I say to you, that Elijah is come already, and they knew him not, but did to him whatever they would” (Matthew 17:12 a).
b “Even so will the Son of man also suffer of them” (Matthew 17:12 b).
a Then the disciples understood that he spoke to them of John the Baptist (Matthew 17:13).
Note than in ‘a' Jesus commanded them, and in the parallel they understood what He meant. In ‘b' He refers to the resurrection of the Son of Man, and in the parallel to the prior death of the Son of Man. In ‘c' is the question about the coming of Elijah, and in the parallel is the answer that Elijah has indeed come. Centrally in ‘d' is the emphasis that the Scripture must be fulfilled.