“Elijah is coming and will restore all things.” Jesus knew that John the Baptist was “Elijah.” Here Jesus used the words of the doctrinal formula commonly used about Elijah by the religious leaders. They would say, “Elijah is coming and will restore all things,” and they were correct in saying that Elijah would come, but they missed him when he came because they were expecting “Elijah” to do things that the Elijah of the Old Testament did, such as raise the dead and confront the government in power at the time, things that John the Baptist was not called to do. So by the time Jesus was speaking to his disciples here after the Transfiguration, he had already come. The Scribes had not been wrong when they said “Elijah is coming,” they just did not know to whom they referred and thus missed it when he was among them. Jesus, however, knew that “Elijah” was John the Baptist, as is clear from Matt. 17:12-13.

In this verse, Jesus was referencing the promise in Malachi that Elijah would come. The verb “will restore” (#600 ἀποκαταστήσει) appears here in the same form as in the Septuagint text, an echo of the fact that Jesus, speaking Hebrew or Aramaic, would have been using the same vocabulary as Malachi. The apostles were not confused by Jesus saying John “will restore” things because they knew the Old Testament text and Jesus immediately followed up what he said by adding that “Elijah” was John. Since John was already dead (see Matt. 14:1ff), it was clear that the restoration work that John did in turning the hearts of the people back to God was done. That restoration work was now left to Jesus. We learn from Mark that John the Baptist came to restore things, and he did baptize many people and turn them back to God, but neither he nor Jesus Christ could turn the nation back to God. Jesus suffered and died so that those who did turn to God and believed could have everlasting life (see commentary on Mark 9:12).