NOTES for Mat 17:10-18
It is not so easy to distinguish prophecy from prediction, and in response to the Lord Jesus Christ's words about the Resurrection, the disciples ask Him about Elijah's coming. After the disciples see Moses and Elijah speaking with Him at the Lord's Transfiguration, they remember Malachi's prophecy and ask the Lord Jesus their question. Perhaps the disciples understand the prophecy too literally. This is the first thing the Lord tells them, pointing out that this prophecy was fulfilled in John the Baptist, the prophet in the spirit and power of Elijah. This is how the disciples understand Christ, and this view was generally accepted in the apostolic age. Later interpreters, however, considered Christ's answer incorrect and began to insist that Elijah would come before the second coming, just as John came before the first.
But the main point in Christ's answer is something else. He shifts the conversation from what God was supposed to fulfill, and whether He fulfilled it, to how people receive His messengers. In modern terms, the problem is not whether God fulfilled Malachi's prophecy with enough precision, but that people did not recognize His messenger, did not receive his preaching, and killed him. The meaning of prophecy, then, is not literal fulfillment, but that we may become participants in the foretold work of God.