Is Hell eternal, or do some/all escape it?

According to the Westminster Confession of Faith, hell is (1) real and (2) eternal.

(for relevant Bible verses, visit the Westminister Confession of Faith links)

Chapter 32, Section 1

I. The bodies of men, after death, return to dust, and see corruption:1 but their souls, which neither die nor sleep, having an immortal subsistence, immediately return to God who gave them:2 the souls of the righteous, being then made perfect in holiness, are received into the highest heavens, where they behold the face of God, in light and glory, waiting for the full redemption of their bodies.[3] And the souls of the wicked are cast into hell, where they remain in torments and utter darkness, reserved to the judgment of the great day.[4] Beside these two places, for souls separated from their bodies, the Scripture acknowledges none.

Chapter 33, Section 2

II. The end of God's appointing this day is for the manifestation of the glory of His mercy, in the eternal salvation of the elect; and of His justice, in the damnation of the reprobate, who are wicked and disobedient. For then shall the righteous go into everlasting life, and receive that fulness of joy and refreshing, which shall come from the presence of the Lord; but the wicked who know not God, and obey not the Gospel of Jesus Christ, shall be cast into eternal torments, and be punished with everlasting destruction from the presence of the Lord, and from the glory of His power.[5]

First you have to understand God's nature which is that He is just and right.

Deuteronomy 32:4

"The Rock, his work is perfect; For all his ways are justice: A God of faithfulness and without iniquity, Just and right is He."

God is just in creating Hell since God can do nothing apart from his nature and God justly gave us free will and "all have sinned and fall short of the glory of God" Romans 3:23

Now some escape deserved eternal damnation due to Christ's sacrifice but that is getting into justification which this question is not about.

Hell is eternal: Matthew 25:41

Depart from me, you cursed, into the eternal fire prepared for the devil and his angels

I do not know of any scripture which states that we can jump back and forth between the 'eternal fire' and heaven. Therefore as far as Rob Bell and his book (I have not read it) goes I do not believe his statements reflect the truth of the Bible.

God is all ruling therefore He rules over the universe but he has also given us free will and the opportunity to sin. He wants us to chose Him but he cannot force us, at best he can harden peoples' hearts who have already not chosen him or he can divinely influence us (Grace).

Assignment to heaven and hell indeed imply certain states of mind. (Cf. the excellent novella by C. S. Lewis treating this very topic, The Great Divorce.) However, the traditional understanding of the afterlife is that those who have died experience a foretaste of what awaits them in the general resurrection occurring upon the second and glorious coming of Christ Jesus. Here are some thoughts that I hope clarify this issue:

First of all, upon Christ's death upon the Cross,

⁵² ...the graves were opened; and many bodies of the saints which slept arose, ⁵³ and came out of the graves after his resurrection, and went into the holy city, and appeared unto many. (Matthew 27:52-53, KJV)

Presumably these had not exactly committed their lives to Christ, but only hoped on the Lord God and looked forward to the day that God would raise up a horn for His people, and died in this hope. It is thus not a stretch to envision God raising to life the righteous of cultures less privileged than the Hebrews, let alone less privileged than the church, Christ's very Body.

Second, God is just, and not just by fiat. We know by experience that Christ is indeed the most fully qualified Judge, for he judges impartially, not following His own will, but that of His Father, the very Author of justice. Indeed, if we merely look at His life among us in the gospels, we see a just man. So we should not despair that God would do injustice, for that is not in His character. We also know God appoints all things for the benefit of those whom He loves, viz. those that He created. So if someone should perish outside the Gospel, then perhaps he would have resisted it had he heard it, and it would have been accounted to him as a greater condemnation.

Third, no one will be in Hell who has not chosen to be there. Even Christ, Who despoiled Hell, chose to be there for our salvation (for only He could leave it, having no sin). Furthermore, God respects the free will of His creatures, and He allows those who choose to live apart from Him do so, if indeed such existence can be called life. If someone consistently and unrepentantly refuses the love of God, then God help such a person, for he has torn down the very bridge to salvation that is repentance. One may very well imagine that such a condition could, like a black hole, collapse irreversibly and irredeemably upon itself, setting someone in a permanent condition of ever-growing antipathy to God. (There are positively terrifying examples of this in Lewis's aforementioned work.) This is hell, and a place is appointed for such, and the place is also hell.

With regards to thinking about the eternality of heaven and hell, one would be a fool not to work for salvation now, which, as Tolstoy puts it, is the only time in which we have any power to act. The gravity of what is at stake is so great that indulging in wishful thinking about what salvation may come later can be disastrous. If it is your own salvation you are thinking about, then yes, heaven and hell are eternal. And indeed they are eternal. Time ends when the resurrection comes, and with time goes all hope for work towards salvation. If ever you have opportunity for salvation, seize it now!

However, if you are distressed about the eternal destination of a neighbor, then pray for that neighbor. Many stories (at least in Eastern Orthodoxy) tell of saints who foresaw perdition for the dead and earnestly prayed God that such a fate would be averted, and God answered their prayer and restored even the truly dead to true life. For example, I think one of the Sts. Gregory thought Emperor Trajan had misunderstood Christians and shouldn't be sent to hell, and earnestly prayed Christ that he would escape this. Also, more recently St. Silouan of Mt. Athos prayed to God that his incorrigibly vindictive elder would escape hell, and God answered his prayer too.

In conclusion, recall these eschatological verses:

¹³Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is.
¹⁴If any man's work abide which he hath built thereupon, he shall receive a reward.
¹⁵If any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire. (1 Corinthians 3:13-15, KJV)

Also recall the Lucan parable of the minas/pounds.

¹²A certain nobleman went into a far country to receive for himself a kingdom, and to return.
¹³And he called his ten servants, and delivered them ten pounds, and said unto them, Occupy till I come.

¹⁴But his citizens hated him, and sent a message after him, saying, We will not have this man to reign over us. ¹⁵And it came to pass, that when he was returned, having received the kingdom, then he commanded these servants to be called unto him, to whom he had given the money, that he might know how much every man had gained by trading.
¹⁶Then came the first, saying, Lord, thy pound hath gained ten pounds. ¹⁷And he said unto him, Well, thou good servant: because thou hast been faithful in a very little, have thou authority over ten cities. ¹⁸And the second came, saying, Lord, thy pound hath gained five pounds. ¹⁹And he said likewise to him, Be thou also over five cities.

²⁰And another came, saying, Lord, behold, here is thy pound, which I have kept laid up in a napkin: ²¹For I feared thee, because thou art an austere man: thou takest up that thou layedst not down, and reapest that thou didst not sow.

²²And he saith unto him, Out of thine own mouth will I judge thee, thou wicked servant. Thou knewest that I was an austere man, taking up that I laid not down, and reaping that I did not sow:
²³Wherefore then gavest not thou my money into the bank, that at my coming I might have required mine own with usury?

²⁴And he said unto them that stood by, Take from him the pound, and give it to him that hath ten pounds.

²⁵(And they said unto him, Lord, he hath ten pounds.)

²⁶For I say unto you, That unto every one which hath shall be given; and from him that hath not, even that he hath shall be taken away from him.

²⁷But those mine enemies, which would not that I should reign over them, bring hither, and slay them before me.

(Luke 19:12-27, KJV)

So some are saved comparatively handily; some are saved truly as if through fire; and yet some still spurn the love of God, even eternally.

There are two major schools about the place, whether it is eternal or whether there is annihilation. Most of the time, Jesus refers to being 'destroyed' in hell. With this definition, only two groups will have an 'eternal' hell. First, Satan and demons. In terms of people, then according to Rev. 14:11:

And the smoke of their torment rises for ever and ever. There is no rest day or night for those who worship the beast and his image, or for anyone who receives the mark of his name.

Not the greatest source always, but Wikipedia provides the following introduction to annihilationism: http://en.wikipedia.org/wiki/Annihilationism

There are a lot of people who also believe this. I'm not going to try to convert you one way or the other, but please be aware that though the majority of Christians believe in Hell, not all believe in eternal torment.

EDIT:

As for who escapes it, Jesus says in John 3:16-17:

¹⁶For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life. ¹⁷For God did not send his Son into the world to condemn the world, but to save the world through him.

If we're thinking about it in the sense of annihilationism, therefore, the only ones that will go on to eternal life are those that believe in God's only Son, Jesus Christ. Will all be saved, will there be a second chance? I wouldn't want to argue for that, but read Francis Chan's book for more (see other comments).

That hell is a literal place as is understood by Western Protestants is far from settled. Byzantine (Greek) Orthodoxy, for example, adheres to a conception of Hell very similar to that espoused by Bell: Hell not a physical place but the state of not experiencing God's love, one can leave it at any time by accepting God's love, and those who live a righteous life without the guidance of God and the Church are quite praiseworthy indeed and can end up in heaven. In fact, within Byzantine Orthodoxy there is a significant push towards a position of universal reconciliation, in which all souls are eventually reconciled with God no matter what their bearers did in life.

The answers above indicating that there is a literal hell and that it is inescapable are written in ignorance of the full spectrum of thought on the matter across all of Christendom. Those quoting Revelations are missing the fact that Revelations was not written as an end-times prophecy but as an allegory for contemporary Christians to help them deal with the persecution they were then facing.

Even within mainstream Christendom there is nothing near universal agreement on this matter as others have suggested.

According to scripture, hell is real, and anyone who was not born again will not enter the Kingdom of Heaven.

41“Then he will say to those on his left, ‘Depart from me, you cursed, into the eternal fire prepared for the devil and his angels. 42For I was hungry and you gave me no food, I was thirsty and you gave me no drink, 43I was a stranger and you did not welcome me, naked and you did not clothe me, sick and in prison and you did not visit me.’ 44Then they also will answer, saying, ‘Lord, when did we see you hungry or thirsty or a stranger or naked or sick or in prison, and did not minister to you?’ 45Then he will answer them, saying, ‘Truly, I say to you, as you did not do it to one of the least of these, you did not do it to me.’ 46And these will go away into eternal punishment, but the righteous into eternal life.” - Matthew 25:41-46 ESV

14Then death and Hades were thrown into the lake of fire. The lake of fire is the second death. 15If anyone’s name was not found written in the book of life, he was thrown into the lake of fire. - Revelation 20:14-15

This clearly states that anyone who does not follow Christ and accept Him into their heart will go to hell. It's inconvenient, but nowhere does it say that following him will be convenient. Anyone who thinks they have an expert knowledge of God is silly. God is too big for man to understand. We have the gift of prayer and his word to find answers in.

Francis Chan did a wonderful job of explaining this on YouTube.