The theory of re-incarnation is nowhere taught in the scriptures. Our Lord Jesus and the Apostles never, in all their teachings, said a word about re-incarnation. As to the meaning of the Savior's words referred to in the question, we recognize that He was calling to mind the prophecy of `Mal. 4:5,6`. John the Baptist was one of the greatest of the prophets, and it was his mission to prepare the way of the Messiah, the Christ, by performing a reformation work in preaching repentance and baptism for the remission of sins, and declaring the kingdom of heaven at hand. This message was to the Jews and to them only, as they had been the Lord's chosen people for many centuries. But now a new dispensation was about to be ushered in. The kingdom of heaven was at hand. And it was John's mission to prepare the people for the new order of things. This He did in the power and spirit of Elijah. (`Luke 1:16,17`.) We know positively that John was not Elijah for we have his own testimony on the subject. "And they asked him, what then? Art thou Elijah? And he saith, I am not. Art thou that prophet? And he answered, No." (`John 1:21.`)