Gehenna refers to The Valley of the son of Hinnom which is just outside Jerusalem. A selection of verses showing that the Bible uses the term the fire of Gehenna to indicate total destruction.
Kings of Israel burned their sons in the Valley of the son of Hinnom:
3 Moreover he burnt incense in the valley of the son of Hinnom, and burnt his children in the fire, according to the abominations of the nations whom the LORD cast out before the children of Israel.
6 He also made his children to pass through the fire in the valley of the son of Hinnom. He practised sorcery, divination, and witchcraft, and dealt with those who had familiar spirits and with wizards. He did much evil in the LORD’s sight, to provoke him to anger.
King Josiah prevented child sacrifice in the Valley of the son of Hinnom:
10 He defiled Topheth, which is in the valley of the children of Hinnom, that no man might make his son or his daughter to pass through the fire to Molech.
The dead bodies of those who have trangressed against God end up fire that won't be quenched:
24 “They will go out, and look at the dead bodies of the men who have transgressed against me; for their worm will not die, nor will their fire be quenched, and they will be loathsome to all mankind.”
The Valley of the son of Hinnom is associated with idolatry, fire rituals and child sacrifices in the prophet Jeremiah's time. He tells us that the idea of burning people has never entered God's mind:
30 “For the children of Judah have done that which is evil in my sight,” says the LORD. “They have set their abominations in the house which is called by my name, to defile it. 31 They have built the high places of Topheth, which is in the valley of the son of Hinnom, to burn their sons and their daughters in the fire; which I didn’t command, nor did it come into my mind.
Jesus warns that we may end up destroyed in Gehenna fire for various reasons:
22 But I tell you that everyone who is angry with his brother without a cause will be in danger of the judgement. Whoever says to his brother, ‘Raca!’ will be in danger of the council. Whoever says, ‘You fool!’ will be in danger of the fire of Gehenna.
43 If your hand causes you to stumble, cut it off. It is better for you to enter into life maimed, rather than having your two hands to go into Gehenna, into the unquenchable fire, 44 ‘where their worm doesn’t die, and the fire is not quenched.’
Referring to the scribes and Pharisees as serpents, Jesus warns them of their coming destruction:
33 You serpents, you offspring of vipers, how will you escape the judgement of Gehenna?
The apostle James uses the term in a similar symbolic way:
6 And the tongue is a fire. The world of iniquity amongst our members is the tongue, which defiles the whole body, and sets on fire the course of nature, and is set on fire by Gehenna.
The apostle Jude refers to the total destruction of Sodom and Gomorrah as suffering the vengeance of eternal fire:
7 Even as Sodom and Gomorrah and the cities around them, having in the same way as these given themselves over to sexual immorality and gone after strange flesh, are shown as an example, suffering the punishment of eternal fire.
These chapters have links to this theme: