The Angel Gabriel said of John:
17 Also, he will go before him with Elijah's spirit and power, to turn back the hearts of fathers to children and the disobedient ones to the practical wisdom of righteous ones, to get ready for [the] Lord a prepared people (Luke 1).
The ‘him’ was Jesus. The prepared people were those whom John baptised in the river Jordan. Zechariah, John’s dad, prophesied about his son saying:
70 Just as he, through the mouth of his holy prophets from of old, has spoken
71 of a salvation from our enemies and from the hand of all those hating us;
72 to perform the mercy in connection with our forefathers and to call to mind his holy covenant,
73 the oath that he swore to Abraham our forefather,
74 to grant us,
after we have been rescued from the hands of enemies, the privilege of fearlessly rendering sacred service to him
75 with loyalty and righteousness before him all our days (Luke 1).
The holy covenant sworn to Abraham referred to here was the Second Abrahamic Covenant for a priesthood in the Kingdom of God (rendering sacred service fearlessly) - see intro28. One cannot fearlessly render service to God in this system, because becoming a true Christian involves persecution which will of necessity involve an element of fear. Jesus confirms this saying:
38 And whoever does not accept his torture stake and follow after me is not worthy of me (Matthew 10).
Therefore this fearless service is occurring in the Kingdom of God after we have been rescued from the hands of our enemies, the chief one of whom is Satan. Our rescue from him is the entrance into God’s kingdom which lasts 1,000 years during most of which time Satan is imprisoned in the second death which is Gehenna!
2 And he seized the dragon, the original serpent, who is the Devil and Satan,
and bound him for a thousand years.
3 And he hurled him into the abyss and shut [it] and sealed [it] over him, that he might not mislead the nations anymore until the thousand years were ended.
After these things he must be let loose for a little while.
4 And I saw thrones, and there were those who sat down on them, and power of judging was given them. Yes, I saw the souls of those executed with the ax for the witness they bore to Jesus and for speaking about God, and those who had worshiped neither the wild beast nor its image and who had not received the mark upon their forehead and upon their hand. And they came to life and ruled as kings with the Christ for a thousand years (Revelation 20).
So the ‘salvation from our enemies’ is the entrance into the 1,000 year kingdom and this is through the Abrahamic covenant. So John must be providing this salvation, so he must be baptising people into this covenant. Hence we read:
5 Then Jerusalem and all Judea and all the country around the Jordan made their way out to him,
6 and people were baptized by him in the Jordan River, openly confessing their sins.
7 When he caught sight of many of the Pharisees and Sadducees coming to the baptism, he said to them: You offspring of vipers, who has intimated to you to flee from the coming wrath?
8 So then produce fruit that befits repentance.
9 And do not presume to say to yourselves: As a father we have Abraham. For I say to you that God is able to raise up children to Abraham from these stones (Matthew 3).
God was raising up children to Abraham through the second abrahamic covenant. These kids were judicially dead stones in the temple of the first true Christian religion. John was warning the Pharisees that although they were physical sons of Abraham, they were not the real sons of Abraham, who are none other than the ‘sons’ through the 1AC, ICC of the ACP and JAC of the AAP. Peter said to the men of Israel at the temple:
25 You are the sons of the prophets and of the covenant which God covenanted with your forefathers, saying to Abraham: And in your seed all the families of the earth will be blessed.
26 To you first God, after raising up his Servant, sent him forth to bless you by turning each one away from your wicked deeds (Acts 3).
But the men of Israel, the physical sons of Abraham had Jesus sent to them first to turn them from their wicked deeds. These physical sons, all of whom were born into the Land and Circumcision Covenant see - [The 1st 2nd and 3rd Ransom and Abrahamic Covenants], had an exclusive on entrance into the First Abrahamic Covenant, until the Land and Circumcision Covenant ended. It ended in 36 CE (AD) Tishri 18 (Sunday 28th September), 3½ years after Jesus died, at the Conversion of Cornelius, a Roman (Acts 10) see [150]. He was the first Gentile to be baptised into the First Abrahamic Covenant.
Luke describes John’s activities as follows:
3 So he came into all the country around the Jordan, preaching baptism of repentance for forgiveness of sins,
4 just as it is written in the book of the words of Isaiah the prophet: ‘Listen! Someone is crying out in the wilderness:
Prepare the way of [the] Lord, you people, make his roads straight.
5 Every gully must be filled up, and every mountain and hill leveled down, and the curves must become straight ways and the rough places smooth ways.
6 And all flesh will see the saving means of God.’
7 Therefore he began to say to the crowds coming out to be baptized by him: You offspring of vipers, who has intimated to you to flee from the coming wrath?
8 Therefore produce fruits that befit repentance. And do not start saying within yourselves: As a father we have Abraham. For I say to you that God has power to raise up children to Abraham from these stones (Luke 3).
Again John is baptising people to become Abraham’s children, in a new sense. They were obviously genetically Abraham’s physical children, and parties to the Circumcision Abrahamic Covenant which was exclusively for his genetic kids, promising them possession of the promised land, and requiring them to be circumcised. But John was constituting those whom he baptised to be Abraham’s children in another way. This way was that they were not genetic sons of the Land and Circumcision Covenant but sons of the First Abrahamic Covenant through their faith.
So this was John the Baptist’s role. It was to create a new true people of God. A new set of children to Abraham. He was baptised ‘from heaven’ to baptise physical sons of Israel, sons of the Land and Circumcision covenant, into sons of the First Abrahamic covenant, the promise validated by Jesus, and the Second Abrahamic Covenant, validated by Isaac. Such sons are baptised into the name of the father, Abraham - see [13]. Hence we read of him:
5 Look! I am sending to you people Elijah the prophet before the coming of the great and fear-inspiring day of Jehovah.
6 And he must turn the heart of fathers back toward sons, and the heart of sons back toward fathers; in order that I may not come and actually strike the earth with a devoting [of it] to destruction (Malachi 4).
John the Baptist came in Elijah’s spirit and power as we saw at the start of this section. But he was in one sense ‘Elijah’ himself according to Jesus:
13 For all, the Prophets and the Law, prophesied until John.
14 And if you want to accept it, He himself is: Elijah who is destined to come (Matthew 11).
And the Fathers whose hearts he turns back towards their sons are God and Abraham, and the sons whose hearts he turns back towards their fathers are the next or succeeding true people of God, the next or succeeding true Religion, who will have both Abraham and God as their fathers. We will find out that every true Christian Religion has had an Elijah figure who is cleaned from heaven to start a new group of Abraham’s sons by baptism, a new group of God’s true people. Just as in the case of the first true Christian religion and John - see [12].