John 1:21

And they asked him (kai hrwthsan auton). Here the paratactic kai is like the transitional oun (then). What then? (Ti oun;). Argumentative oun like Paul's ti oun in Romans 6:15 . Quid ergo? Art thou Elijah? (Su Elia ei;). The next inevitable question since Elijah had been understood to be the forerunner of the Messiah from Malachi 4:5 . In Mark 9:11 Jesus will identify John with the Elijah of Malachi's prophecy. Why then does John here flatly deny it? Because the expectation was that Elijah would return in person. This John denies. Jesus only asserts that John was Elijah in spirit. Elijah in person they had just seen on the Mount of Transfiguration. He saith (legei). Vivid dramatic present. I am not (ouk eimi). Short and blunt denial. Art thou the prophet? (o prophth ei su;). "The prophet art thou?" This question followed naturally the previous denials. Moses ( Deuteronomy 18:15 ) had spoken of a prophet like unto himself. Christians interpreted this prophet to be the Messiah ( Acts 3:22 ; Acts 7:37 ), but the Jews thought him another forerunner of the Messiah ( John 7:40 ). It is not clear in John 6:15 whether the people identified the expected prophet with the Messiah, though apparently so. Even the Baptist later became puzzled in prison whether Jesus himself was the true Messiah or just one of the forerunners ( Luke 7:19 ). People wondered about Jesus himself whether he was the Messiah or just one of the looked for prophets ( Mark 8:28 ; Matthew 16:14 ). And he answered (kai apekriqh). First aorist passive (deponent passive, sense of voice gone) indicative of apokrinomai, to give a decision from myself, to reply. No (Ou). Shortest possible denial.