I think it was imperative that John the Baptist did not know that he was Elijah. In essence this area of the bible to me was on the doctrine of reincarnation. Hardly can anybody realise that he is a reincarnation. The Jews were well aware of the prophecy in Malachi 4:5, therefore, If John the Baptist had realised that he was Elijah and profess such to the Jews and they believed in him, then they would have believed Jesus was the Messiah, the Saviour, and he would not have been crucified for the redemption of our sins. Jesus crucifixion was a major constituent of the mission of the Messiah.
