John 1:21

What then? John’s denial left unanswered the basic question as to his authority for preaching.

Art thou Elias? It was popularly believed that Elijah would appear in person to proclaim the coming of Messiah (Matt. 17:10; DA 422; cf. Mishnah Shekalim 2.5, Soncino ed. of the Talmud, p. 8; Eduyoth 8.7, Soncino ed. of the Talmud, p. 50; Baba Mezia 1.8; 2.8; 3.4, 5, Soncino ed. of the Talmud, pp. 124, 181, 223, 224; etc.).

I am not. John affirmed that he had come to do the work the prophets of old had foretold Elijah would do (John 1:23; cf. Mal. 3:1; 4:5; Mark 1:2, 3), but he would have been misunderstood had he claimed to be Elijah. It was foretold of John that he was to go before Messiah “in the spirit and power of Elias” (Luke 1:17). For Christ’s declaration that John was Elias see on Matt. 11:14; 17:12.

That prophet. Literally, “the prophet,” that is, the prophet foretold by Moses in Deut. 18:15 (see comment there). There was a popular belief that Moses would be raised from the dead, and some apparently wondered whether John might be he (see DA 135). Later, the people thought the same thing of Jesus (John 6:14; 7:40; cf. Acts 3:22; 7:37).