Burning is the most terrible punishment and brings the most intense pain and torment with it…All imaginable pleasures on earth will never prevail with the but one half-hour in a burning fiery furnace nor would all the wealth in the world prevail with the most covetous to do it. Yet on much lower terms do most men, in effect, expose themselves to everlasting fire in hell, which is more vehement and terrible than any fire we on earth are acquainted with. This will appear by the following considerations:
(1) As in heaven, grace being brought to its perfection, profit and pleasure also arrive at their height there; so sin, being come to its height in hell, the evil of punishment also arrives at its perfection there. Wherefore, as the joys of heaven are far greater than any joys that the saints obtain on earth, so the punishments of hell must be greater than any earthly torments whatever…
(2) Why are the things of another world represented to us in an earthly dress…? The weakness of our capacities in such matters, which the Lord is pleased to condescend unto, requires it. It [is] always supposed that the things of the other world are in their kind more perfect than those by which they are represented…When therefore we hear of hellfire, it is necessary [that] we understand by it something more vehement, piercing, and tormenting than any fire ever seen by our eyes…Hell-torments are represented under the notion of fire, which the damned are cast into. A dreadful representation indeed!…We hear also of “the second death” (Rev 20:6), for the damned in hell shall be ever dying; of the “wine-press of the wrath of God” (Rev 14:19), wherein they will be trodden in anger, trampled in the Lord’s fury (Isa 63:3)—pressed, broken, and bruised without end; “the worm that dieth not” (Mar 9:44), which shall eternally gnaw them; “a bottomless pit,” where they will be ever sinking (Rev 20:3). It is not simply called “a fire,” but “the lake of fire and brimstone” (20:10), “a lake of fire burning with brimstone” (19:20)— one can imagine nothing more dreadful. Yet, because fire gives light, and light, as Solomon observes (Ecc 11:7), is sweet, there is no light there, but darkness—utter darkness (Mat 25:30). They must have an everlasting night, since nothing can be there that is in any measure comfortable or refreshing.
(3) Our fire cannot affect a spirit but by way of sympathy with the body to which it is united. But hellfire will not only pierce into the bodies, but directly into the souls of the damned. For it is “prepared for the devil and his angels,” those wicked spirits whom no fire on earth can hurt…How vehement must that fire be that pierces directly into the soul and makes an everlasting burning in the spirit, the most lively and tender part of a man wherein wounds or pains are most intolerable!
(4) The preparation of this fire proves the inexpressible vehemency and dreadfulness of it. The text calls it “prepared” fire, the prepared fire by way of eminence. The three were not cast into ordinary fire, but a fire prepared for a particular purpose. Therefore, [it] was exceeding hot, the furnace being heated seven times more than ordinary (Dan 3:19-22). [Likewise,] the damned shall find in hell a prepared fire, the like to which was never prepared by human art. It is a fire of God’s own preparing, the product of infinite wisdom with a particular purpose: to demonstrate the most strict and severe divine justice against sin…As the things He has prepared for them that love Him are great and good beyond expression or conception, so one may conclude that the things He has prepared against those who hate Him are great and terrible beyond what men can either say or think of them, God Himself will be a consuming fire to the damned (Deu 4:2). [He will be] intimately present as a devouring fire in the souls and bodies. It is a fearful thing to fall into a fire or to be shut up in a fiery furnace on earth. But the terror of these vanishes when we consider how fearful it is to fall into the hands of the living God, which is the lot of the damned. “Who among us shall dwell with the devouring fire? who among us shall dwell with everlasting burnings?” (Isa 33:14).
Thomas Boston (1676-1732) “Of Hell” in The Complete Works of Thomas Boston, Vol. 8, reprinted by Tentmaker Publishing, http://www.tentmaker.org.uk.