He is Elijah

John the Baptist is in prison because he has condemned Herod Antipas for taking Herodias, his brother's wife, to be his own.

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It is often said that hell has no fury like a woman scorned; Herodias had surely a hand in John's imprisonment.

It is now Jesus' turn to bear testimony to John who had given testimony to the people that Jesus is the One who is to come.

Jesus describes John as a reed that does not sway with the wind, a man of principle like himself who is truthful and is not concerned with anyone's opinion, and who does not regard a person's status (Mt 22:16).

Secondly, John lives the austerity of a true prophet of God, at home in his desert surroundings, and foreswearing the comfort of the Temple (John was of priestly lineage).

Thirdly, he embodies the prophet Elijah, the champion of God's sovereignty during the reign of Ahab and Jezebel.

In fact, he is Elijah who is to come, the fulfillment of Malachi's prophecy about Elijah being sent to prepare the people for the day of the Lord (Mal 3:1).