As John Day discusses in his book on the god Moloch, it is well known that in Jewish literature and in the NT, Gehenna is a term for the fiery portion of the underworld where the resurrected dead are destined to be punished (e.g. 4 Ezra 7:36; 2 Baruch 59:10, 85:13; Mark 9:43, 45, 47), and Gehenna itself derives from the Aramaic name for the valley of Hinnom, Gehinnam, the valley to the southeast of Jerusalem. As an eschatological term, Gehenna is constantly associated with fires that bring punishment to the wicked. What is the origin of this concept?
There is a popular notion (endorsed by the Watchtower Society) that Gehenna became the term for Hell because there was a garbage dump there which was constantly being burnt up by an incinerator and that corpses were thrown onto it. However, besides the fact that cremation was unusual for the time, there is no archaeological support for this view and no ancient writer mentions it. It is found for the first time only about A.D. 1200 in Kimhi's commentary on Psalm 27:13:
"And it was a despised place where they cast filth and corpses, and there was there perpetually a fire for the burning of the filth and the bones of the corpses. On account of this, the judgment place of the wicked is parabolically called Gehenna" (David Kimhi, Commentary, Ps. 27:13)
Archaeological evidence however clearly shows that the valley of Hinnom was instead utilized in the first century (and for a thousand years before) as cemetary grounds, containing thousands of tombs and graves (not exactly the most respectful place for a garbage dump). The oldest biblical text (dating from before the Babylonian Exile) in fact comes from a tomb in the Hinnom Valley. Jeremiah 7:32, 31:40 also appears to attest its use as burial grounds. In view of the lack of any material evidence and historical evidence, Kimhi's claim appears to have been a late medieval attempt to explain the meaning of Gehenna.
The only fires that are certainly attested in connection with the valley of Hinnom are those associated with the sacrifices offered to the god Molech. Jeremiah 32:35 thus refers to idolators who "have built the high places of Baal in the Valley of ben-Hinnom, there to make their sons and daughters pass through fire in honor of Molech," and King Josiah is said to have "desecrated the furnace in the Valley of ben-Hinnom, so that no one could make his son or daughter pass through fire in honor of Molech" (2 Kings 23:10; cf. Leviticus 18:21, 20:2-5; Isaiah 30:33, 57:9). We also read in Jeremiah:
"They have built the high place of Topheth in the Valley of ben-Hinnom, to burn their sons and daughters; a thing I never commanded, a thing that never entered my thoughts. So now days are coming -- it is Yahweh who speaks -- when people will no longer talk to Topheth or the Valley of ben-Hinnom, but of the Valley of Slaughter. Topheth will become a burial ground, for lack of other space" (Jeremiah 7:31-33)
"They have filled this place with the blood of the innocent....So now the days are coming -- it is Yahweh who speaks -- when people will no longer talk to Topheth or the Valley of ben-Hinnom, but of the Valley of Slaughter" (Jeremiah 19:4-6).
The name Topheth is cognate with Aramaic tapya and Syriac tepaya meaning "place of fire", "oven", and "furance", and this meaning is perfectly consistent with Isaiah 30:33, where Yahweh promises to "set fire" to Topheth, "like a stream of brimestone". The idea in Jeremiah 7:32-34 that Topheth will be crammed with the bodies of the dead idolators anticipates the later eschatological conception. The most important fact that contributed to the eschatological conception is that the valleys running down from Mount Zion were thought to represent Sheol. This was first pointed out by J. A. Montgomery in a JBL article published in 1908. In the OT, Zion was frequently equated with the mountain of Paradise (cf. Psalm 46:5; Isaiah 8:6; Ezekiel 47:1-12; Joel 4:18; Zecharaiah 14:8; Isaiah 11:6-9, 65:25; compare Revelation 21:10-22:2), and note that Gihon is the name of both the paradisiacal river in Genesis 2:13 and the spring in Mount Zion; similarly the "mountain of God" is equated with Eden in Ezekiel 28:12. According to Isaiah 14:12-15, Sheol lies at the base of this divine cosmic mountain, and it is only natural for the deep valley below it to be associated with the underworld. Note also that a valley adjoining the Hinnom valley is called the Valley of the Rephaim in Joshua 15:8, 18:16; 2 Samuel 5:18, 23:13; 1 Chronicles 11:15, 20:4 and the Rephaim were the ghosts of the dead residing in Sheol (cf. Job 26:5-6; Isaiah 14:4-5, 9-11, 26:14). The earthly valleys associated with the underworld also evoke the "valleys of Sheol" where the Rephaim are found:
"The fellow does not realize that here the Rephaim are gathered, that her guests are heading for the valleys of Sheol" (Proverbs 9:18; cf. 2:18, 9:18)
This close association with the valleys near Jerusalem and Sheol explains why the Molech cult was practiced in this locale. As John Day explains with textual and archaeological evidence, Molech was a god of the underworld and was identified with the Akkadian god Nergal. This is why we read in Isaiah 57:9 that "with oil you made yourself look your best for Molech, lavishing your scents; you sent your envoys far afield, down to Sheol itself". The association with Molech and the underworld is even preserved in the Quran, where we encounter Malik as an angel of hell, to whom the damned appeal in order that he intercede with Allah (Quran, sura 43:77). Since Molech was a god of the underworld (Sheol), it is not too difficult to understand how fiery sacrifices associated with him in the Hinnom valley developed into the notion of the fires of the hellish Gehenna.
The notion of a fiery judgment developed not as a doctrine of an immortal, disembodied soul, but as part of the doctrine of the resurrection, as immortality, in a post-exilic Jewish context, was tied to the hope of a resurrection (cf. Wisdom 3:4; 2 Maccabees 7:9, 16-17; Daniel 12). The earliest reference to eternal fire, in Isaiah 66:22-24 refers only to "the corpses of men who have rebelled against [Yahweh]," so initially the belief was apparently centered only on the everlasting destruction of the dead body. When the belief in the resurrection began to take hold, some (such as the writers of 2 Maccabees and the Testament of Job 4:7-11) limited the resurrection as a reward to the righteous. But most viewed the resurrection as twofold; the eschatological belief was that at the time of the end (e.g. Judgment Day), the resurrection would bring "some to everlasting life and some to shame and everlasting disgrace." (Daniel 12:2). The Testament of Benjamin (second century B.C.) similarly foretold:
"And then you will see Enoch and Seth and Abraham and Isaac and Jacob being raised up at the right hand in great joy. Then shall we be raised, each of us over our tribe, and we shall prostrate ourselves before the heavenly King. Then all shall be changed, some destined for glory, others for dishonor, for the Lord first judges Israel for the wrong she has committed and then he shall do the same for all the nations." (Testament of Benjamin 10:6-11)
According to 2 Baruch 50:2-54:21, the righteous would be changed "into the splendor of angels" but the wicked would be resurrected in grotesque, "horrible shapes" and "shall suffer the torment of judgment" so that "a retribution will be demanded with regard to those who have done wicked deeds". Again, the concept of hell is part of the belief in the final resurrection. Similarly, Matthew 25:46 refers to the wicked going "away to eternal punishment and the virtuous to eternal life," and John 5:27-29 says that "the Son of Man has been appointed supreme judge, for the hour is coming when the dead will leave their graves at the sound of his voice: those who did good will rise again to life and those who did evil to condemnation". Revelation 20:11-15 gives an extended vision of the resurrection of the dead, Hades being emptied of its dead, followed by the judgment of dead, and the eternal punishment of the resurrected wicked in the lake of fire.
The late Jewish and NT conception of Gehenna similarly drew on this notion of the resurrection. Thus Jesus specifies that both "soul and body" and the "body" would go to the "judgment" of Gehenna -- that is, after the resurrection (Matthew 5:29, 10:28, 23:33). This has nothing to do with punishment of a disembodied immortal soul; it is punishment of a resurrected person, of both body and spirit. Other Jewish apocalypses describe the Gehenna that the resurrected wicked will face:
This accursed valley [e.g. Gehenna] is for those accursed forever; here will gather together all those accursed ones, those who speak with their mouths unbecoming words against the Lord and utter hard words concerning his glory. Here shall they be gathered together, and here shall be their judgment, in the last days. There will be upon them the spectacle of the righteous judgment, in the presence of the righteous forever....There was produced from that bronze and fire a smell of sulfur which blended with those waters. This valley of the perversive angels shall continue to burn punitively underneath that ground....The Most High will arise on that day of judgment in order to execute a great judgment upon all the sinners...Woe unto you sinners, when you oppress the righteous ones, in the day of hard anguish, and burn them with fire! You shall be recompensed according to your deeds. On account of the deeds of your wicked ones, in blazing fires worse than fire it shall burn ....You yourselves know that they will bring your souls down to Sheol and they shall experience evil and great tribulation--in darkness, nets, and burning flame. Your souls shall enter into the great judgment; it shall be a great judgment in all the generations of the world. (1 Enoch 27:2-3, 100:4-9, 103:7-8; cf. Jude 7, 14-15, which quotes 1 Enoch to specifically refer to this judgment on the wicked)
I will burn with fire those who mocked them and ruled over them in this age...I have prepared them to be food for the fire of Hades, and to be ceaseless soaring in the air of the underworld regions of the uttermost depths, to the contents of a wormy belly....For they shall putrefy in the belly of the crafty worm Azazel, and be bburned by the fire of Azazel's tongue....And behold, in this light a fiery Gehenna was enkindled, and a great crowd in the likeness of men. They were all changing in aspect and shape, running and changing form and prostrating themselves and crying aloud words I did not know. (Apocalypse of Abraham 15:6-7, 31:2-6)
The souls of the wicked are brought down to Sheol by two angels of destruction, Za'api'el and Samki'el....Za'api'el is appointed to bring down the souls of the wicked from the presence of the Holy One, blessed be he, from the judgment of the Sekinah, to Sheol, to punish them with the fire in Gehinnom, with rods of burning coal. (3 Enoch 44:2-3)
The Lord will come with his angels and with the armies of the holy ones of the seventh heaven and with the glory of the seventh heaven, and he will drag Beliar into Gehenna and also his armies, ... the Beloved will cause fire to go forth from him, and it will consume all the godless. (Ascension of Isaiah 4:14, 18)
"And the earth shall give up those who are asleep in it; and the chambers shall give up the souls which have been committed to them. And the Most High shall be revealed upon the seat of judgment, and compassion shall pass away, and patience shall be withdrawn, but judgment alone shall remain, truth shall stand, and faithfulness shall grow strong.... Then the pit of torment shall appear, and opposite it shall be the place of rest; and the furnace of Gehenna shall be disclosed, and opposite it the Paradise of delight. Then the Most High will say to the nations that have been raised from the dead, 'Look on this side and on that, here are delight and rest, and there are fire and torments!' " (4 Ezra 7:32-38).
Gehenna is copiously described in rabbinical literature. It was thought to have several gates, one in the valley of Hinnom and other in Jerusalem ('Erubin 19a), likely drawing on Isaiah 31:9 which refers to Yahweh having "his furance in Jerusalem". The entrance into Gehenna is narrow but underneath Gehenna extends infinitely (Menahot 99b), and "the whole world is like a lid for Gehenna" (Pesahim 94a). The fire in Gehenna is 60 times as hot as any terrestial fire (Berakot 57b). Regarding the punative nature of Gehenna, God declares: "I punish the slanderers from above, and I also punish them from below with glowing coals" ('Ar. 15b). That the Pharisees believed in such a concept of everlasting punishment is also evident from Josephus, Antiquities 18.1.3, and eschatological Gehenna appears in the synoptic Gospels as an already-established notion that Jesus draws on in his teaching.