For the Christianity experts: When people go to hell, is it for all eternity or only temporarily? Can you provide the relevant Bible quotes?

It is for eternity,  there are no second chances

In both testaments, hell is the grave for the body, Hebrew sheol and Greek hades. It is eternal. The body decomposes there. It will never return from the grave.


The spirit returns to God for judgment. The wicked and unbelieving spirits are cast into the lake of fire where they are annihilated forever. Scripture calls this the second death, death of the spirit.


Revelation 21:8 KJV — But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death.


Revelation 2:11 KJV — He that hath an ear, let him hear what the Spirit saith unto the churches; He that overcometh shall not be hurt of the second death.

This is as near a description as I could find in a hurry.

Matt 25:46 “Then they will go away to eternal punishment, but the righteous to eternal life. ”

 Sure the eternal punishment is he'll itself. 

Jesus repeatedly referred to Hell as "everlasting" and "eternal". It's right there in the Bible!

Eternity.  Google Bible verses about eternal hell .

The Hell There Is

“The doctrine of hell is so frightening that numerous heretical sects end up denying the reality of an eternal hell. The Unitarian-Universalists, the Seventh-day Adventists, the Jehovah’s Witnesses, the Christadelphians, the Christian Scientists, the Religious Scientists, the New Agers, and the Mormons—all have rejected or modified the doctrine of hell so radically that it is no longer a serious threat.

But the eternal nature of hell is stressed in the New Testament. For example, in Mark 9:47–48 Jesus warns us, “[I]t is better for you to enter the kingdom of God with one eye than with two eyes to be thrown into hell, where the worm does not die, and the fire is not quenched.” And in Revelation 14:11, we read: “And the smoke of their torment goes up for ever and ever;

Hell is not just a theoretical possibility. Jesus warns us that real people go there. He says, “Enter by the narrow gate; for the gate is wide and the way is easy, that leads to destruction

The teaching of the Church affirms the existence of hell and its eternity. Immediately after death the souls of those who die in a state of mortal sin descend into hell, where they suffer the punishments of hell, ‘eternal fire.’ 

https://www.catholic.com/tract/the-hell-there-is?ref=patrick.net

https://www.youtube.com/watch?v=0XRsuoyIr_I
Initial Christians didn't believe in eternal suffering. 

Here the answer: https://www.jw.org/finder?wtlocale=E&docid=502013346&srcid=share

I am not going to consider myself an expert, so you can disregard this post if you want. There are many more skilled in their understanding of scripture than I am. I suppose you are referring to the Lake of Fire and not the Grave (aka Hell) in the bible. The Lake of Fire is the ultimate place of judgment for the unrighteous. It is called, the "second death".

It is very evident that those who take the mark of the beast, the beast himself, the false prophet and the devil will be cast into the Lake of Fire. These will burn eternally before God, and their smoke will rise up, it says, before him forever. (Rev 14)

Logically, since the unrighteous dead are raised from the dead for judgment, why would there be no eternal punishment? Why not just leave them in torment if they are going to literally die in a few moments in a lake of fire after the time of judgment? (Acts 24:15, John 5:28,29) That makes no sense. Instead, we see that they too are cast into the Lake of Fire. (Revelation 14:10: 19:20; 20:10 and 21:8)

They are conscious (Revelation 20:10) and gnashing their teeth. If it was not a continual state of agony, there would be no gnashing of teeth. They would just die.

Why then mention those who will burn forever in the lake of fire before God and not clump the others in there with them? I believe it because most people will be suffering eternally in outer darkness, while those mentioned in my second paragraph will be suffering in the presence of God. There is a difference. (Rev 22:15)

Keep in mind that there is no passage of time in eternity. In eternity, the past, present and future are all the same unceasing moment. If you have been in eternity for even one second then you have been there forever. We can't comprehend a place where there is no passage of time because all we have ever known is time. Time had a beginning, and it began with the creation of the physical world. It doesn't make any sense to say this, but there was a time when there was no time.

Eternity is a state of being. Like I said, it is impossible to grasp a place without the passage of time. We just can't identify with it.

So yes, people go to hell forever. But what is forever? What's that like?