His name is John, will go on before the Lord to prepare the way of him

Luke 1:57-80
His name is John. Both Zechariah and Elizabeth said.
Everyone who heard this wondered about it, asking, 'What then is this child going to be? For the Lord's hand was with him.
And you, my child, will be called a prophet of the Most High; for you will go on before the Lord to prepare the way of him, to give his people the knowledge of salvation through the forgiveness of their sins, because of the tender mercy of our God, by which the rising sun will come to us from heaven to shine on those living in darkness and in the shadow of death, to guide our feet into the path of peace. Zechariah's song.
Neither Mark nor John is interested in the stories of Jesus' birth, and Matthew focuses on Jesus as the Messiah, from the royal line of David, and his fuller account of Jesus' birth adds much to what we know. He must surely have interviewed Mary, Jesus' mother, to have obtained such privileged information. The language and ideas of these chapters reflect his Jewish sources.
The fact that the child was not to be given a family name, and Zechariah's sudden recovery of speech as the Holy Spirit fills him, giving his pent-up thoughts voice in prophetic song, make a deep impression on the people around, Great thing are now expected of John.
Why?
God's blessing and guiding is on John's family, the Holy Spirit is be with them.
People knew that the Lord's hand was with him for there is miracle happened on them.
Baptist John will prepare the way of Jesus, his mission is give his people the knowledge of salvation through the forgiveness of their sins.
Zechariah has prophet what his son will be through his song praise the Lord Alimght.
How?
Follow the way of Holy Spirit's guidenace and don't care the word of population.