The following is a critique of Bishop N.T. Wright’s interpretation of the significance of Gehenna. His views on it are quoted from his book: N.T. Wright, Surprised by Hope: Rethinking Heaven, the Resurrection, and the Mission of the Church. HarperOne, 2008. p. 175-178.
In most popular English translations, the word Gehenna in Matthew 5:29, 30, and elsewhere in the New Testament is translated hell. However, this is improper, as indicated by the way Gehenna is handled in other languages. In translations of this verse, the word is often left untranslated. Since Gehenna is the name of a specific valley near Jerusalem, leaving it untranslated is obviously more correct. The table below presents the translations of Matthew 5:29 in various languages, where the word Gehenna was left untranslated.
Arthur W. Pink compared Gehenna with the lake of fire in Revelation 20 in his article on Eternal Punishment. He thought these two things were identical. But Pink may have been mistaken about this, as he was about the doctrine of dispensationalism. He eventually realized dispensationalism was false, and wrote a series of articles against that theory, which he previously supported.
The city of Jerusalem is one of the most prominent of all places mentioned in scripture, and in the New Testament, Jerusalem is the name of the church, and its location is heaven, not upon the earth. The various locations and landforms associated with the promised land are the setting for the revelations of God in scripture. These revelations include the gospel, and the promise and hope of the future resurrection.
Isaiah 22 is titled “The burden of the valley of vision.” A curious feature of this chapter is that while it is a prophecy about the valley of vision, it describes the desolation of Jerusalem, which naturally leads us to wonder what might the significance of a “valley” might be. Why is it called “the valley of vision“? Most commentators agree that the prophecy in this chapter is about Jerusalem. In Isaiah 2:1-3, the prophet identifies Jerusalem, and the hill of Zion, with “the mountain of the Lord’s house,” which he says will be established in the tops of the mountains. Paradoxically, in chapter 22 he refers to Jerusalem as a valley. How can it be both a valley, and a mountain?
Interpretations of Gehenna that appeal to events of 70 AD miss the significance of the prophecies of Jeremiah about the future of the valley of Hinnom, which say that it will become “holy unto the Lord.” This is easily understood, when Jesus’ references to Gehenna are seen in the context of a judgment, which those who are accounted unworthy to enter the kingdom of heaven and the holy city must endure.
Jerusalem and Gehenna are two key geographical locations in the promised land, crucial for understanding the Gospel, and the mysteries of present and future judgment. In a post on Gehenna and Eschatology, part of a series on Questioning Hell, Randy Olds wrote:
N.T. Wright, author of Surprised by Hope, was Bishop of Durham 2003-2010, and is now Professor of New Testament and Early Christianity at the University of St Andrews in Scotland. On the meaning of Gehenna, he wrote: 
Many Bible scholars assume that when Jesus mentioned “Gehenna,” he referred to the common idea of “hell,” a place of unending infernal misery for the wicked.
To support the traditional belief, these Bible scholars have investigated the meaning of “Gehenna,” hoping to show how the word was interpreted by Jews in the time of Jesus. They claim that the use of the word by the Jews, reveals the use that Jesus made of it.
The New World Translation of Mark 9:43-48 by the JWs has:
43 “And if ever your hand makes you stumble, cut it off; it is finer for you to enter into life maimed than with two hands to go off into Ge·hen´na, into the fire that cannot be put out. 44 — 45 And if your foot makes you stumble, cut it off; it is finer for you to enter into life lame than with two feet to be pitched into Ge·hen´na. 46 — 47 And if your eye makes you stumble, throw it away; it is finer for you to enter one-eyed into the kingdom of God than with two eyes to be pitched into Ge·hen´na, 48 where their maggot does not die and the fire is not put out.
In every case where most English versions have “hell,” they use the word Ge·hen´na, which is a place name, so ought not to have been translated “hell,” which is an interpretation rather than a translation. Also, as indicted in the NWT version above, the insertion of verses 44 & 46 is suspect; they are omitted in the following versions:
The land promise God gave to Abraham, and to Isaac, and to Jacob, is the great theme of the Old Testament, but to many, it appears to be strangely absent in the New. Walter Brueggemann, an Old Testament scholar, said: 
In the interpretation of New Testament references to Gehenna proposed by Walter Balfour, it was a figure or an emblem that represented the destruction that came upon the Jewish nation in 70 AD. He wrote: 
The following is part of Walter Balfour’s discussion of Gehenna, in which he shows that it cannot designate a place of endless torment for the wicked. This exert is from:
Todd Bolen, in an article about the significance of Gehenna in the New Testament, claimed that it represents “the place of everlasting fiery torment.” He suggested that the idea that Gehenna was a garbage dump with fires continually burning, has little or no archeological nor literary evidence to support it. The trash dump idea was attributed Rabbi David Kimchi in AD 1200.
In his Commentary on Matthew, Mark, and Luke, John Calvin identified Gehenna with hell. He wrote on the word Gehenna used by Jesus in Matthew 5:22: 
The following is the first of two parts of an account of the controversy about Universalism in New England in the early nineteenth century, written by Frank H. Foster.
The following is the second of a two part account of the controversy about Universalism in New England in the early nineteenth century, written by Frank H. Foster.
Revelation 12:16 says the earth that opens her mouth, and swallows up the flood that the serpent casts out of his mouth, to carry away the woman, who represents the church. The word earth in the Greek is Ge, which can also mean land. I suggest that the land that swallows up the flood from the serpent’s mouth, a flood of false doctrine and flawed interpretations, alludes to the promised land, which in the new covenant, is called a better country, that is, an heavenly one. [Hebrews 11:16] It represents promises of spiritual things, and the eternal inheritance of the saints. Read more…
The following is an enlightening discussion of Gehenna by John Wesley Hanson. According to a recent post on the Dave Enjoys blog, content of chapter 3 of Rob Bell’s book ‘Love Wins’ is very reminiscent of Hanson’s work.
Steve Holmes, a Baptist minister, and theology professor at St Mary’s College, St Andrews, Scotland, has been reviewing Rob Bell’s book, Love Wins, on his blog Shored Fragments. In the seventh part of an on-going series he examined Bell’s chapter 3, a discussion of hell.