There are three ways to understand the flames of hell. They can be a literal fire. They can be a metaphorical fire. And they can be a consuming fire (the annihilationist view). The third view states that the fire of hell completely destroys sinners, so they cease to exist. I want to deal with the first two views here since they are more common.
The Literal View teaches that hell is a place of eternal, conscious torment. The Old Testament does not have an explicit teaching on hell, but does speak about the afterlife. The Hebrew sheol and the Greek hades are used to signify the dwelling place of the dead or simply the “grave.” So Deut 32:22 states that “For a fire has been kindled in my wrath, one that burns to the realm of death below. It will devour the earth and its harvests and set afire the foundation of its mountains.” Some theologians have taught that sheol has two compartments, one for the wicked and one for the righteous. Jesus seems to hint at this in the parable of the rich man and Lazarus (Luke 16:19-21).
The word gehenna is the most common and clear word used to denote hell. Of the twelve times this word is used in the New Testament, eleven are from Jesus’ teachings and the other is from James. Gehenna actually referred to the Valley of Hinnom, south of Jerusalem, where garbage was perpetually burned. So the image of a burning garbage dump was the image associated with hell.
Jesus frequently used gehenna and the image of fire to warn of the judgment of God on sinners. Trees that bear bad fruit are thrown “into the fire (Matt 3:10).” The wicked will go into “eternal fire (Matt 25:41).” Branches that are not connected to Christ are thrown “into the fire (John 15:6).” Because fire is the most stated form of punishment in the afterlife, it is appropriate to conclude that hell is a literal fire that is experienced by unregenerated sinners.
One of the key passages for a literal view of hell is Rev 20:10-15. Christians are told that the beast and the false prophet are “tormented day and night for ever and ever (Rev 20:10).” As for the wicked who are in hades awaiting judgment, after their judgment (v. 13) they are “thrown into the lake of fire (v. 14).” Then in 21:8, the wicked are again seen in the “fiery lake of burning sulfur.” These vivid descriptions of fire support the conclusion that hell is a literal fire that burns its occupants forever .
The Metaphorical View of hell teaches that hell is not literally a “lake of fire” but it is a place of eternal, conscious punishment. Fire is used as a metaphor very frequently in ancient writings. Paul uses it to symbolize judgment and sexual desire (1Cor 3:15, 7:9). James uses it to symbolize sinful words (Jam 3:6). It is therefore very appropriate that Jesus used the term gehenna, signifying the Valley of Hinnom, as a symbolic representation of hell. It was a desecrated place, due to its use for child sacrifices to the Ammonite god, Molech (2Chron 28:3). Jeremiah later cursed the valley (Jer 19). In Jesus’ time, it was a place to burn garbage, using sulfur as a flammable substance.
There are different metaphors for hell besides the Valley of Hinnom. Jesus compared it to many beatings, worms that never die, and weeping and gnashing of teeth (Luke 12:47, Mark 9:48, Matt 8:12). Jude compares hell to eternal fire and blackest darkness (Jude 1:7, 13). How can fire produce darkness? Even more problematic, how can a whole lake of fire produce darkness? And if spirit beings like Satan and his demons are there (Matt 25:41), how does physical fire hurt them? This variety of descriptions of hell points to the conclusion that hell is not a literal fire but still a terrible place of God’s eternal wrath.
Personally, I lean towards a Metaphorical View of hell. At the very least, the fire must have different properties than the fire we are familiar with. But keep in mind that if fire is the best way to explain hell, then the reality would be just as horrible, if not more so! Either way, we ought to feel the terrible reality of hell. When we do this, we are prompted to proclaim the Good News that Christ has made a relationship with God possible through the cross! Praise God there is no condemnation for those that are in Christ Jesus!