To clarify the expressions used—furnace of fire, Gehenna of fire, outer darkness, weeping and gnashing of teeth—Jesus portrayed the destiny of sinners before His audience, stating that those condemned at the end of the age would be thrown into the furnace of fire, a place of sorrow and despair. The question arises whether the term ‘furnace of fire’ should be understood literally or as a metaphor for the suffering that awaits sinners. It appears that these expressions can only be regarded as literal if Jesus consistently spoke about the future of sinners in this manner. However, we see that on other occasions, such as in the Sermon on the Mount, He depicted the misery of sinners as being in the valley of fire (Matt. 5:29). Later, while discussing the fate of the Jews, He mentioned their expulsion into outer darkness, where there will be weeping and gnashing of teeth, indicating that many will come from the east and west to recline with Abraham, Isaac, and Jacob in the kingdom of heaven (Matt. 8:11-12).
The imagery of burning in a fiery furnace was familiar to Jesus' listeners from the Old Testament. For instance, Judah, the son of Jacob, condemned his daughter-in-law Tamar to be burned (Gen. 38:24), while David had the conquered inhabitants of Rabbah executed by fire (2 Samuel 12:31). Nebuchadnezzar ordered that Ananias, Mishael, and Azariah be thrown into a fiery furnace for refusing to worship a golden idol (Dan. 3:21). In ancient Eastern societies, burning alive was a common and agonizing form of capital punishment. Therefore, when Jesus spoke about the grave punishment awaiting sinners in eternal life, He used the image of the fiery furnace to vividly convey the severity of their fate should they not repent and experience rebirth.
Later, when responding to the Sadducees regarding the resurrection, Jesus compared those who would be raised to angels or spirits in preparation for the Last Judgment, explaining that the resurrected bodies would not resemble the physical forms we inhabit in this life (Lk. 20:27-36). Thus, it can be inferred that the sufferings experienced by the condemned would be more of a mental nature rather than purely physical.