The NT uses several terms to depict the condition of the dead. The term hades is employed 10 times to designate the abode of the dead or the tomb. In many ways this use reminds one of the ways the OT writers use sheol to refer to the resting place of the dead. Neither sheol nor hades designate in the Bible an eternal place of fiery torture for the wicked, except perhaps in Luke 16:23.
The NT says that the city of Capernaum will be brought down to hades (Matt. 11:23; Luke 10:15); that is to say to the realm of death, thus indicating its destruction. Jesus tells Peter that the gates of hades will not prevail against the church (Matt. 16:18), meaning that the church will prevail against the forces of death. God did not abandon Jesus in hades, meaning that Jesus did not remain in the tomb (Acts 2:27, 31). Jesus has the keys of death and hades, referring to the tomb as the resting place of the dead (Rev. 1:18). Hades followed the symbolic rider Death, to indicate that those who die will go to the place of the dead (6:8). Death and hades (the tombs) will give up their dead at the resurrection (20:13). And death and hades will get thrown into the lake of fire (v. 14). This last passage shows that hades does not refer to a fiery place for the punishment of the wicked; hades itself is cast into the lake of fire in order to show that death and hades will come to a permanent end. Thus hades, as used in the NT, is almost another way of saying “death” or “the grave.” Only the parable of the rich man and Lazarus, a popular story among the Jews which was used by Jesus, describes hades as a place of punishment (Luke 16:23). The acceptance of the concept of the immortality of the soul among some Jews opened the door for them to understand hades as a place of punishment for the wicked.
The term gehenna, appearing 12 times in the NT, does have connotations of punishment. It is the Grecized form of the Hebrew Gê Hinnom, “Valley of Hinnom,” a gorge south of Jerusalem. The OT mentions it in such passages as Joshua 15:8; 2 Kings 23:10; 2 Chron. 33:6; and Jer. 7:31. The valley became the site of the pagan ritual of sacrificing children by fire (2 Chron. 28:3; 33: 6). Jeremiah, alluding to the practice, said that God would make the “valley of the son of Hinnom” to be known as “the valley of Slaughter” (Jer. 7:32). So many bodies would be buried there that it would soon run out of room, and the rest of the bodies would have to be left for animal scavengers to dispose of (vv. 32-33). Perhaps because of his prophecy, during the intertestamental period the name of the valley came to represent the eschatological place of judgment (1 Enoch 26–27; 54:1-6; 56:1-4; 90:24-27).
Also, during this period there developed in Judaism the notion of a fiery judgment (1 Enoch 10:13; 48:8-10; 100:7-9; 108:4-7; 2 Baruch 85:13). Such a judgment usually took place in a fiery lake or abyss (1 Enoch 18:9-16; 90:24-27; 103:7-8; 2 Enoch 40:12; 2 Baruch 59: 5-12; 1 Qh 3). The association of gehenna with fiery destruction and judgment led people to use the word metaphorically for hell or eternal damnation (2 Esdras 7:26-38; 2 Baruch 85:13). Some have also seen in rabbinical tradition the valley as a place for burning carcasses and rubbish.
All the references to gehenna in the NT, with the exception of James 3:6, appear in the sayings of Jesus in the Synoptic Gospels. Three occur in the Sermon on the Mount (Matt. 5:22, 29-30). Matt. 10:28 warns believers that they should “fear Him who is able to destroy both soul and body in hell [gehenna].” In Matt. 18:9 Jesus speaks of “hell [gehenna] fire.” Jesus asks the Pharisees in Matt. 23:33 whether they can “escape the condemnation of hell [gehenna].” Also, He states that it is better to be maimed than to wind up in gehenna (Mark 9:43-45, 47). Luke 12:5 clearly has something beyond death in mind. One is cast into hell [gehenna] after being killed. Gehenna refers to what John calls the lake of fire that at the end will destroys Satan and the wicked (Rev. 20:14-15). The expression “Son of hell [gehenna]” (Matt. 23:15) describes a convert to Judaism as being even more intolerant than the Pharisees who had led him to keep their traditions. The single usage of gehenna outside the Gospels (James 3:6) describes the tongue being symbolically set on fire by gehenna.
Matthew 3:12 compares sinners to chaff burned with an unquenchable fire. Chaff flares up instantly and vanishes. If Jesus had wanted to stress a continuing fire, He could have chosen a better illustration by referring to something that was not immediately consumed, such as smoldering embers. In Matt. 25:31-46, Jesus speaks of the judgment of the nations. It is the only place in the NT that defines the criteria He will use to categorize the redeemed and the lost. Those who do not show love and concern for others He symbolically places at His left hand, the inferior position in the Middle Eastern mind-set. He will say to the wicked, “Depart from Me, you cursed, into the everlasting fire prepared for the devil and his angels” (v. 41). Jesus concludes the passage by announcing that “these [the lost] will go away into everlasting punishment, but the righteous into eternal life” (v. 46). The effects or results of the punishment are eternal.