20 He confessed and did not deny it, but confessed, "I am not the Messiah." [1] 21 And they asked him, "What then? Are you Elijah?" He said, "I am not." "Are you the prophet?" He answered, "No." 22 Then they said to him, "Who are you? Let us have an answer for those who sent us. What do you say about yourself?" 23 He said, "I am the voice of one crying out in the wilderness, "Make straight the way of the Lord,' " as the prophet Isaiah said. 24 Now they had been sent from the Pharisees.
Matthew Henry's Commentary on John 1:20-24
Commentary on John 1:19-28
(Read John 1:19-28)
John disowns himself to be the Christ, who was now expected and waited for. He came in the spirit and power of Elias, but he was not the person of Elias. John was not that Prophet whom Moses said the Lord would raise up to them of their brethren, like unto him. He was not such a prophet as they expected, who would rescue them from the Romans. He gave such an account of himself, as might excite and awaken them to hearken to him. He baptized the people with water as a profession of repentance, and as an outward sign of the spiritual blessings to be conferred on them by the Messiah, who was in the midst of them, though they knew him not, and to whom he was unworthy to render the meanest service.