Jude 7 speaks of the ancient cities of Sodom and Gomorrah having received the “vengeance of eternal fire” for their sins.

Jud 1:6  And the angels who did not keep their proper domain, but left their own abode, He has reserved in everlasting chains under darkness for the judgment of the great day;
Jud 1:7  as Sodom and Gomorrah, and the cities around them in a similar manner to these, having given themselves over to sexual immorality and gone after strange flesh, are set forth as an example, suffering the vengeance of eternal [aionios] fire.

The Greek word translated “eternal” is aionios which means perpetual, everlasting, eternal.

What is this eternal fire?  Are the inhabitants of ancient Sodom and Gomorrah still burning in some eternal hell fire?

It should be understood first that mankind is mortal.  The dead have no thoughts or consciousness but must be resurrected to live again, see “Do you have an immortal soul?”.  So certainly, the inhabitants of ancient Sodom and Gomorrah are dead and not still suffering.

So we ask again, what is this eternal fire? 

Some argue that it means the destruction of the cities was eternal, not the people.  But this doesn’t make sense as both the buildings and the people were destroyed by the same eternal fire. 

Others argue that it means the fire’s effect is everlasting.  But the fire’s effect is not everlasting on them, because the people of Sodom and Gomorrah will rise again in the day of judgment, as shown by the Scriptures below.

Mat 10:14  And whoever will not receive you nor hear your words, when you depart from that house or city, shake off the dust from your feet.
Mat 10:15  Assuredly, I say to you, it will be more tolerable for the land of Sodom and Gomorrah in the day of judgment than for that city!

Mat 11:23  And you, Capernaum, who are exalted to heaven, will be brought down to Hades; for if the mighty works which were done in you had been done in Sodom, it would have remained until this day.
Mat 11:24  But I say to you that it shall be more tolerable for the land of Sodom in the day of judgment than for you.”

The eternal fate of those people who lived in Sodom and Gomorrah has not yet been decided.  They will rise in the second resurrection, where they will be judged according to how they live their lives.

Rev 20:12  And I saw the dead, small and great, standing before God, and books were opened. And another book was opened, which is the Book of Life. And the dead were judged according to their works, by the things which were written in the books.
Rev 20:13  The sea gave up the dead who were in it, and Death and Hades delivered up the dead who were in them. And they were judged, each one according to his works.

What then is the explanation of the eternal fire of Jude 7? 

As mentioned at the start, the Greek word translated eternal in Jude 7 is aionios.  The same Greek word is used many times to describe eternal life.  If Scripture is consistent then both the eternal fire and the eternal life have the same quality of being eternal.  Just as eternal [aionios] is used to describe life, so this same word is used to describe fire.  It is the fire that is eternal.  God used eternal fire to destroy Sodom and Gomorrah. 

The same eternal fire is mentioned in Mat 18:8.

Mat 18:8  “If your hand or foot causes you to sin, cut it off and cast it from you. It is better for you to enter into life lame or maimed, rather than having two hands or two feet, to be cast into the everlasting [aionios] fire.

The everlasting fire will consume those thrown into it.  This is the same event spoken of in Revelation.

Rev 20:14  Then Death and Hades were cast into the lake of fire. This is the second death.
Rev 20:15  And anyone not found written in the Book of Life was cast into the lake of fire.

Rev 21:8  But the cowardly, unbelieving, abominable, murderers, sexually immoral, sorcerers, idolaters, and all liars shall have their part in the lake which burns with fire and brimstone, which is the second death.”

The same eternal fire is also mentioned Mat 25:41.

Mat 25:41  “Then He will also say to those on the left hand, ‘Depart from Me, you cursed, into the everlasting [aionios] fire prepared for the devil and his angels:

The everlasting fire will be used on the devil and his angels.  Everlasting refers to the fire, not how long the devil and his angels experience the fire.  This is the same event spoken of in Revelation.

Rev 19:20  Then the beast was captured, and with him the false prophet who worked signs in his presence, by which he deceived those who received the mark of the beast and those who worshiped his image. These two were cast alive into the lake of fire burning with brimstone.

Rev 20:9  They went up on the breadth of the earth and surrounded the camp of the saints and the beloved city. And fire came down from God out of heaven and devoured them.
Rev 20:10  The devil, who deceived them, was cast into the lake of fire and brimstone where the beast and the false prophet are. And they will be tormented day and night forever and ever.

It is a lake of fire and brimstone.  The Greek word translated brimstone means sulphur.  Fire and brimstone are what God rained down on Sodom and Gomorrah.

Gen 19:24  Then the LORD rained brimstone and fire on Sodom and Gomorrah, from the LORD out of the heavens.

The Hebrew word translated brimstone means resin or something equally inflammable, by analogy sulphur.

What is under the thin crust of the earth?  The mantle and under that the core.   The mantle is very hot dense rock, and the core is very hot molten metals.  Is this lake of fire?  There are many places on earth now where earth’s thin crust opens up and the molten rock can be seen.  Were Sodom and Gomorrah destroyed by a volcanic eruption? 

Is the “eternal fire” and the “lake of fire” hot molten lava? If so, then in what way is this eternal? There seem to be two possible explanations.

1) This eternal hot molten lava goes on and on forever at the centre of the earth and it continues in some fashion in the distant future when God creates a new heaven and a new earth.

2) This eternal hot molten lava goes on and on until the “new earth”.  It is eternal only in the context of the life on this present earth.

The devil and his angels are spirit and are not constrained or hurt by physical fire.  The implication is that they will be turned to flesh because Satan will be burned and turned to ashes.  Ezekiel 28 describes an anointed cherub, Satan, who was created perfect but sinned.

Eze 28:14  “You were the anointed cherub who covers; I established you; You were on the holy mountain of God; You walked back and forth in the midst of fiery stones.
Eze 28:15  You were perfect in your ways from the day you were created, Till iniquity was found in you.

God cast this cherub out of His presence.

Eze 28:16  “By the abundance of your trading You became filled with violence within, And you sinned; Therefore I cast you as a profane thing Out of the mountain of God; And I destroyed you, O covering cherub, From the midst of the fiery stones.
Eze 28:17  “Your heart was lifted up because of your beauty; You corrupted your wisdom for the sake of your splendor; I cast you to the ground, I laid you before kings, That they might gaze at you.

The unfortunate end of this cherub is destruction by fire until there is nothing left but ashes.

Eze 28:18  “You defiled your sanctuaries By the multitude of your iniquities, By the iniquity of your trading; Therefore I brought fire from your midst; It devoured you, And I turned you to ashes upon the earth In the sight of all who saw you.