John 1:19-24 And this is the record of John, when the Jews sent priests and Levites from Jerusalem to ask him, Who art thou? And he confessed, and denied not; but confessed, I am not the Christ. And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No. Then said they unto him, Who art thou? that we may give an answer to them that sent us. What say thou of thyself? He said, I am the voice of one crying in the wilderness, Make straight the way of the Lord, as said the prophet Esaias. And they which were sent were of the Pharisees.
John the Baptist was not the Christ, Elijah, or anyone else who had lived in the past. He was the natural son of Zacharias and Elizabeth (Lk. 1:24, 1:57). He came in the spirit and power of Elijah to do for Israel before the first coming, what Elijah will do before the second coming (Mal. 4:5-6; Lk. 1:17). This explains Matthew 11:14 and 17:10-13.
He was the prophet that Moses predicted would come (Deu. 18:15-18; Acts 3:22-23; 7:37).
‘I am the voice of one crying in the wilderness, make straight the way of the Lord, as said the prophet Esaias’ is the first Old Testament prophecy fulfilled in the gospel of John.
Malachi 3:1 predicted of John “Behold, I will send my messenger, and he shall prepare the way before me: and the Lord, whom you seek, shall suddenly come to his temple, even the messenger of the covenant, whom you delight in: behold, he shall come, saith the LORD of hosts.”