Thank you for contacting BibleAsk.
The answer to the question: “Why did John say he was not Elijah when Jesus said he was?” is found in Luke 1:13-17. The angel who announced John’s birth said, “Thy wife Elisabeth shall bear thee a son, and thou shalt call his name John. … He shall be great in the sight of the Lord. … And he shall go before him in the spirit and power of Elias (“Elias” is the Greek form of “Elijah”) , to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just; to make ready a people prepared for the Lord” (Verses 13-17).
Elijah, in days of apostasy and crisis, (1 Kings 17:1; 18:1–19, 36–40) was a symbol of reformation and loyalty to God. And the nature of the work of John the Baptist, as the forerunner of the Messiah, was prophesied in the scriptures (Isa. 40:1–11; Mal. 3:1; 4:5, 6). Even the scribes recognized that “Elias must first come” before the coming of the Messiah (Matt. 17:10; Mark 9:11, 12). John’s message was one of reform and repentance (Matt. 3:1–10).
John resembled Elijah, not only in the work he was to do and in the fearlessness with which he was to proclaim truth (1 Kings 21:17–24; Matt. 3:7–10), but even in his manner of life and in his general appearance (Matt. 3:4; 2 Kings 1:8). And both prophets suffered persecution (1 Kings 18:10; 19:2; Matt. 14:10).
Prophecies concerning the forerunner of the Messiah were so strikingly fulfilled in John the Baptist that the common people and also their leaders recognized the resemblance of John to Elijah (John 1:19–21). Even after the death of John the priests, scribes, and elders did not dare deny that John was a prophet (Matt. 21:24–27; Mark 11:29–33; Luke 20:3–7).
Therefore, when Jesus referred to John as Elijah, He was referring to his life, spirit, power, and work that was similar to Elijah’s. The emphasis is on the message, not the man. So, John was not Elijah in person, but he was presenting the Elijah message of reformation.
In His service,