He will go before him in the spirit and power 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."
And the disobedient to walk in the wisdom of the just ...  This is the same as "turning the hearts of the children to the fathers," as it is stated in Malachi, meaning that they will repent and again honor the faith of their father Abraham.  There is, of course, the obvious fact that much more than metaphor is intended here.  Moses and Elijah who were also among "the fathers," appeared in conversation with Jesus in the transfiguration; and from this the deduction could be made that "the fathers" referred to by the angel in this passage were fully aware of Israel's apostasy, and that the reunification of children and fathers would be a reality, although spiritual, and not merely a figure of speech.  Of course, the envisioned unity would be accomplished only in the persons who would repent and turn to God under John's preaching.