(Darby)
Matt 3:7, "But seeing many of the Pharisees and Sadducees coming to his baptism, he said to them, Offspring of vipers, who has forewarned you to flee from the coming wrath? "

Baptism with the Holy Spirit and Fire

Luke 3:16, John answered, saying unto them all, I indeed baptize you with water; but there cometh he that is mightier than I, the latchet of whose shoes I am not worthy to unloose: he shall baptize you  in the Holy Spirit and in fire (ASV)

John the Baptist’s words at Matthew 3:7 and Luke 3:16 were addressed to the people in general who were surrounding him on that day. Naturally, John addressed the Israelites, all of God’s people then, the Jewish nation at that time. However, we must not make the mistake of limiting the words of John to refer only to the fleshly Israelites; rather, these words must be taken as referring equally to all of God's people, ancient Israel as well as new spiritual Israel.

The passages at Luke 3:9 and Matthew 3:10 both are definite in their usage of being "cast into the fire"– this is a clear reference to destruction for those that are axed down.  Nevertheless, the prophecy being "cast into the fire" points to some future fiery action of Jesus Christ. The phrases "baptize you with . . .fire" and "cast into the fire" are not equal, and they do not refer to the same event.  Baptism with fire, refers to the refining fire of Christ--a long term process; its outcome is individually dependent, but all shall experience it !

Mark 9:49 For, everyone, with fire, shall be salted. (Rotherham)

(DRC)

Luke 3:9, For now the axe is laid to the root of the trees. Every tree therefore that bringeth not forth good fruit, shall be cut down and cast into the fire.

Matthew 3:10, For now the axe is laid to the root of the trees. Every tree therefore that doth not yield good fruit, shall be cut down, and cast into the fire.

When the prophecy at Matthew 3:1 states, “That one will baptize YOU people with holy spirit and with fire,” it refers to God’s people then and now: first, the then existing Jewish nation, whose covenant still was in force, and second, the Spiritual nation of Israel that came into being on Pentecost 33 C.E.

Malachi 3:1, Behold, I send my messenger, and he shall prepare the way before me; and the Lord whom ye seek will suddenly come to his temple, and the Angel of the covenant, whom ye delight in: behold, he cometh, saith Jehovah of hosts. (Darby)

Regarding Jesus Christ and his use of fire, the passage at Malachi chapter 3 is very enlightening. John the Baptist and Jesus knew it revealed their functions vis-á-vis each other and concerned the work Jehovah wanted them to accomplish: John, the messenger, preparing the way for Jesus, the true Lord Refiner described as being “like the fire of a refiner.

Further, in Malachi 3:5, this assurance was issued, “And I will come near to YOU people for the judgment…” Here, the Lord Refiner reveals his dual purpose: that of refining, of purifying his people individually and that of getting rid of the wicked baptizing them with fire.

Malachi 3:2,3, But who shall endure the day of his coming? and who shall stand when he appeareth? For he will be like a refiner's fire, and like fullers' lye. 3And he shall sit as a refiner and purifier of silver; and he will purify the children of Levi, and purge them as gold and silver; and they shall offer unto Jehovah an oblation in righteousness. (Darby)

The fire that the true Lord, Jesus Christ, refines his people with is so intense that Isaiah calls it “the smelting furnace of affliction.” (Isaiah 8:10) Likewise, in Psalm 66:12 is found the phase “We have come through fire and through water.” (also Zech. 13:9)

When considering the scriptures in regard to fire and refining, John the Baptizer's "baptize with fire" may be clearly understood. By John finishing by saying the "chaff he will burn up in fire inextinguishable," (Diaglott ) it is obvious that those not passing the test of refinement shall be considered chaff.

Isaiah 48:10 10Behold, I have refined thee, but not as silver. I have chosen thee in the furnace of affliction. (ACV)

Psalm 66:10, 12, For Thou hast tried us, O God, Thou hast refined us as the refining of silver. (12) Thou hast caused man to ride at our head. We have entered into fire and into water, And Thou bringest us out to a watered place. (YLT)

Zechariah 13:9, And I have brought the third into fire, And refined them like a refining of silver, And have tried them like a trying of gold, It doth call in My name, and I answer it, I have said, `My people it is ,' And it saith, `Jehovah is my God!' (YLY)

That the fire of this Refiner Lord is not only cleansing but also destructive is verified in 1 John 2:19, “ They went out from us, but they were not of our sort; for if they had been of our sort, they would have remained with us. But [they went out] that it might be shown up that not all are of our sort.”?

Vis-á-vis apostates, Jeremiah 6:29-30 says, The bellows blow fiercely, the lead is consumed of the fire. In vain do they go on refining, for the wicked are not plucked away. 30Waste silver, men shall call them, because LORD has rejected them. (ACV)

The true Lord, Jesus Christ, the Refiner, rejected these ones. They didn’t have enough faith and purity. Their end is as Revelation 21:8 explains, “But as for the cowards and those without faith and those who are disgusting in their filth and murderers and fornicators and those practicing spiritism and idolaters and all the liars, their portion will be in the lake that burns with fire and sulphur.” (NW) It is a fiery end.

The Lord Refiner has purified his people individually and collectively. Each remaining individual has passed through fire and water; the furnace of affliction taught each one to desist from sin through suffering. (Ps. 119:67, 71; 1 Pet 4:1) This suffering or trial is like a burning which the Christian is destined for. (1 Pet. 4:12, 1 Thess. 3:4)

Psalm 119:67, Before I was afflicted, I transgressed; therefore have I kept Your word (71) It is good for me that You have afflicted me; that I might learn Your statutes.
In order that I may learn your regulations. (AB)

1 Peter 4:1,. . . because he who has suffered in flesh has ceased from sin. (ACV)

1 Peter 4:12, Beloved, ye should not be surprised at the fieriness in you, which occurs for a trial to you, like a strange thing happening to you. (ACV)

1 Thessalonians 3:4, For, even when we were with you, we told you beforehand—we are destined to suffer tribulation! even as it also came to pass, and ye know. (Rotherham)

Proverbs 27:17, “By iron, iron itself is sharpened. So one man sharpens the face of another (NW)

Collectively Jesus refines his sheep and makes sure that neither wolves nor goats are permitted to remain in his fold. These clearly will suffer the ultimate baptism with fire by being destroyed.

The scriptures about our Lord Refiner, Jesus Christ, then demonstrate that the fire functions to refine, cleanse, and destroy. John the Baptist statement that Jesus will baptize with Holy Spirit and fire then is seen not to simply mean that the fire is destructive; no, it is also a burning away of the filth.

Isaiah 4:4-6 4 When Jehovah will have washed away the excrement of the daughters of Zion and he will rinse away even the bloodshed of Jerusalem from within her by the spirit of judgment and by the spirit of burning down, 5 Jehovah will also certainly create over every established place of Mount Zion and over her convention place a cloud by day and a smoke, and the brightness of a flaming fire by night; because over all the glory there will be a shelter. 6 And there will come to be a booth for a shade by day from the dry heat, and for a refuge and for a hiding place from the rainstorm and from the precipitation. (NW)

Galatians 6:8, Because, he that soweth into his own flesh, out of the flesh, shall reap corruption, whereas, he that soweth into the Spirit, out of the Spirit, shall reap age-abiding life. (Rotherham)