For behold, the Lord will come with fire - The Septuagint reads this 'As fire' (ὡς πύρ hōs pur). Fire is a common emblem to denote the coming of the Lord to judge and punish his enemies Psalm 50:3 :

Our God shall come, and shall not keep silence;

A fire shall devour before him,

And it shall be very tempestuous round about him.

So Habakkuk 2:5 :

Before him went the pestilence,

And burning coals went forth at his feet.

So Psalm 97:3 :

A fire goeth before him,

And burneth up his enemies round about.

So it is said 2 Thessalonians 1:8, that the Lord Jesus will be revealed 'in flaming fire, taking vengeance on them that know not God' (compare Hebrews 10:27; 2 Peter 3:7). So Yahweh is said to breathe out fire when he comes to destroy his foes:

There went up a smoke out of his nostrils,

And fire out of his mouth devoured;

Coals were kindled by it.

The Lord will come with fire "Jehovah shall come as a fire" - For באש baesh, in fire, the Septuagint had in their copy קאש kaesh, as a fire; ὡς πυρ.

To render his anger with fury "To breathe forth his anger in a burning heat" - Instead of להשב lehashib, as pointed by the Masoretes, to render, I understand it as להשב lehashshib, to breathe, from נשב nashab.

For, behold, the Lord will come with fire,.... Either with material fire, with which mystical Babylon or Rome shall be burnt, Revelation 18:8, or with indignation and wrath, which shall be poured out like fire, and be as intolerable and consuming as that:

and with his chariots like a whirlwind; making a great noise, and striking great terror; alluding to chariots in which men used formerly to fight:

to render his anger with fury, and his rebuke with flames of fire; a heap of words, to show the fierceness of his wrath, and how severe his rebuke of enemies will be; which will be not a rebuke in love, as of his own people, but in a way of vindictive wrath.

The prophecy now takes a new turn with the thought expressed in the words, "and fiercely does He treat His enemies." The judgment of wrath, which prepares the way for the redemption and ensures its continuance, is described more minutely in Isaiah 66:15 : "For behold Jehovah, in the fire will He come, and His chariots are like the whirlwind, to pay out His wrath in burning heat, and His threatening passeth into flames of fire." Jehovah comes bâ'ēsh, in igne (Jerome; the lxx, on the contrary, render it arbitrarily ὡς πῦρ kâ'ēsh), since it is the fiery side of His glory, in which He appears, and fire pours from Him, which is primarily the intense excitement of the powers of destruction within God Himself (Isaiah 10:17; Isaiah 30:27; Psalm 18:9), and in these is transformed into cosmical powers of destruction (Isaiah 29:6; Isaiah 30:30; Psalm 18:13). He is compared to a warrior, driving along upon war-chariots resembling stormy wind, which force everything out of their way, and crush to pieces whatever comes under their wheels. The plural מרכּבתיו (His chariots) is probably not merely amplifying, but a strict plural; for Jehovah, the One, can manifest Himself in love or wrath in different places at the same time. The very same substantive clause מרכבתיו וכסופה occurs in Jeremiah 4:13, where it is not used of Jehovah, however, but of the Chaldeans. Observe also that Jeremiah there proceeds immediately with a derivative passage from Habakkuk 1:8. In the following clause denoting the object, אפּו בּחמה להשׁיב, we must not adopt the rendering, "to breathe out His wrath in burning heat" (Hitzig), for hēshı̄bh may mean respirare, but not exspirare (if this were the meaning, it would be better to read להשּׁיב from נשׁב, as Lowth does); nor "ut iram suam furore sedet" (Meier), for even in Job 9:13; Psalm 78:38, עפו השיב does not mean to still or cool His wrath, but to turn it away or take it back; not even "to direct His wrath in burning heat" (Ges., Kn.), for in this sense hēshı̄bh would be connected with an object with ל, אל (Job 15:13), על (Isaiah 1:25). It has rather the meaning reddere in the sense of retribuere (Arab. athâba, syn. shillēm), and "to pay back, or pay out, His wrath" is equivalent to hēshı̄bh nâqâm (Deuteronomy 32:41, Deuteronomy 32:43), Hence עפו בחמה does not stand in a permutative relation instead of a genitive one (viz., in fervore, riâ suâ equals irae suae), but is an adverbial definition, just as in Isaiah 42:25. That the payment of the wrath deserved takes place in burning heat, and His rebuke (ge‛ârâh) in flames of fire, are thoughts that answer to one another.

For, behold, the LORD will come with fire, and with his chariots like a whirlwind, to {q} render his anger with fury, and his rebuke with flames of fire.

(q) This vengeance God began to execute at the destruction of Babylon and has always continued it against the enemies of his Church, and will do till the last day, which will be the accomplishment of it.

66:15 With fire - With terrible judgments, or with fire in a proper sense, understanding it of the fire with which enemies use to consume places brought under their power. Whirlwind - With a sudden sweeping judgment. Fury - That is, with fervour; for fury properly taken is not in God. Rebukes - They had contemned the rebukes of the law, now God will rebuke them with fire, and sword.

Margin render his anger

(Day of Jehovah)

Isa 2:10-22 4:1-6 11:10-13 13:9-16 24:21-23 26:20,21 Isa 63:1-6 66:15-24 Rev 19:11-21

15. (Isa 9:5; Ps 50:3; Hab 3:5; 2Th 1:8; 2Pe 3:7).

chariots . whirlwind-(Jer 4:13).

render-as the Hebrew elsewhere (Job 9:13; Ps 78:38) means to "allay" or "stay wrath." Maurer translates it so here: He stays His anger with nothing but fury," &c.; nothing short of pouring out all His fiery fury will satisfy His wrath.

fury-"burning heat" [Lowth], to which the parallel, "flames of fire," answers.

66:15-24 A prophetic declaration is given of the Lord's vengeance on all enemies of his church, especially that of all antichristian opposers of the gospel in the latter days. Ver.