Luke 1.17: “And it is he who will go as a forerunner before Him in the spirit and power of Elijah, TO TURN THE HEARTS OF THE FATHERS BACK TO THE CHILDREN, and the disobedient to the attitude of the righteous; so as to make ready a people prepared for the Lord.” (NASB)
All four gospels communicate that John the Baptist was the person appointed to go before Jesus to prepare his way. John’s mission was set forth in the prophecy of Isaiah 40 and in the prophecy of Malachi, chapters three and four. The four gospels quote from these Old Testament prophecies about John in their own unique ways. And Luke gives us more detail about how it came to be known that John was the one chosen to be the forerunner of Jesus.
In Luke chapter one the angel Gabriel appeared to John’s father, Zechariah, and told him that he and his wife Elizabeth would have a child. This would be a very unexpected birth because Zechariah and Elizabeth were of old age. Gabriel told him that his son was to be named John and verse 17 above sets forth the mission that was appointed for John. With this understanding Zechariah prophesied at John’s dedication that John would go before the Lord to prepare his ways, all of which is recorded in Luke 1.67-80.
The word “forerunner” is not actually in the original text of verse 17 above and this word is not used in the New Testament with reference to John the Baptist. But this translation supplies this word for the best understanding, because the meaning and mission of what Gabriel tells Zechariah is clear. Likewise, Jesus confirmed to his disciples that John was the one who performed the mission of Elijah who was to come, referenced in Malachi chapter four. A portion of Malachi’s prophecy is contained in Gabriel’s word to Zechariah in verse 17 above, and it is the portion shown in all caps.
As John the Baptist begins his ministry of preparation for Jesus, he will be preaching the message of repentance and sharing the Good News founded upon the prophecies in the Old Testament regarding this mission.