Plan of salvation/What is "endless punishment"
What is "endless punishment"?
Questions and Answers
Question: What is the nature of "endless" or "eternal" punishment?
The Book of Mormon seems to indicate that the suffering of the wicked will go on forever without end
The Lord often uses the phrases "endless punishment," "endless torment," and "eternal damnation" to describe the type of punishment that will be administered to the wicked. It is natural to assume, given our understanding of the words "endless" and "eternal," to believe that punishment would continue forever. In fact, the Book of Mormon states:
And assuredly, as the Lord liveth, for the Lord God hath spoken it, and it is his eternal word, which cannot pass away, that they who are righteous shall be righteous still, and they who are filthy shall be filthy still; wherefore, they who are filthy are the devil and his angels; and they shall go away into everlasting fire, prepared for them; and their torment is as a lake of fire and brimstone, whose flame ascendeth up forever and ever and has no end.
This certainly initially appears to support the idea that the Book of Mormon indicates that the suffering of the wicked will go on forever without end. In fact, Alma's son Corianton was concerned about the nature of this punishment.
And now, my son, I perceive there is somewhat more which doth worry your mind, which ye cannot understand—which is concerning the justice of God in the punishment of the sinner; for ye do try to suppose that it is injustice that the sinner should be consigned to a state of misery.
The Lord clarified the meaning of these terms to Joseph Smith in a revelation given in March, 1830
Alma's response to his son emphasized the need to repent in order to satisfy justice, but he did not elaborate on the exact nature of the punishment that would be administered if one did not repent. The natural concern is the idea that people would be "consigned to suffer throughout all eternity for what was done during the few years of mortality."  Fortunately, the Lord clarified the meaning of these terms to Joseph Smith in a revelation given in March, 1830.
DC 19:4-12 states:
And surely every man must repent or suffer, for I, God, am endless.
Wherefore, I revoke not the judgments which I shall pass, but woes shall go forth, weeping, wailing and gnashing of teeth, yea, to those who are found on my left hand.
Nevertheless, it is not written that there shall be no end to this torment, but it is written endless torment.
Again, it is written eternal damnation; wherefore it is more express than other scriptures, that it might work upon the hearts of the children of men, altogether for my name’s glory.
Wherefore, I will explain unto you this mystery, for it is meet unto you to know even as mine apostles.
I speak unto you that are chosen in this thing, even as one, that you may enter into my rest.
For, behold, the mystery of godliness, how great is it! For, behold, I am endless, and the punishment which is given from my hand is endless punishment, for Endless is my name. Wherefore—
Eternal punishment is God’s punishment.
Endless punishment is God’s punishment.
The Book of Mormon does provide indications that the use of the words "endless" and "eternal" indicate the nature of the punishment rather than its duration, thus contradicting the claims made by the critics. The Lord, through modern revelation, provided clarification on the meaning of the terms "endless" and "eternal" when used to describe punishment. Thus, Latter-day Saints understand "endless punishment" and "eternal punishment" to mean "God's punishment," since "endless" and "eternal" are two of God's names. Likewise, the term "eternal life" can be interpreted to mean "God's life" in the same manner.
Question: What is the meaning of "eternal" life?
Given the "eternal" punishment represents "God's punishment," it stands to reason the "eternal" life refers to "God's life"
Arthur R. Bassett states in the February 1978 Ensign:
The significant relationship between knowing God and eternal life is clarified by the Lord’s explanation to Joseph in 1830 that “Endless” is another name properly applied to Him, and, consequently, that Eternal punishment, or Endless punishment, is God’s punishment. (See D&C 19:10–12.) It seems to follow then that eternal life is God’s life. Therefore, the Prophet’s statement can be taken to mean, in part, that eternal life, being God’s life, is understood only as one comes to know God and Christ. Knowing the Master ultimately seems to mean becoming like the Master. 
Question: Does the Book of Mormon support the idea that "eternal" or "endless" punishment can be temporary?
In the Book of Mormon, Alma's "eternal torment" only lasted three days
The Book of Mormon does indeed provide some indication of the true nature of "eternal" and "endless" punishment. Consider Alma's description of his conversion experience during the three days that he was incapacitated after seeing an angel. Alma says,
I was racked with eternal torment, for my soul was harrowed up to the greatest degree and racked with all my sins. (Alma 36:12) (emphasis added)
Alma's "eternal torment" lasted only three days, which implies that he was describing the nature of his torment rather than its duration. Similarly, in Mosiah 27:28 Alma says
Alma was also removed from a state of "everlasting burning"
Nevertheless, after wading through much tribulation, repenting nigh unto death, the Lord in mercy hath seen fit to snatch me out of an everlasting burning, and I am born of God.
The term "everlasting burning" obviously refers to a state of torment rather than a duration.
In the Book of Mormon, we find:
O the greatness of the mercy of our God, the Holy One of Israel! For he delivereth his saints from that awful monster the devil, and death, and hell, and that lake of fire and brimstone, which is endless torment. 2 Nephi 9:19 (emphasis added)
The statements by Alma and Nephi effectively negate the criticism that the Book of Mormon contradicts Joseph Smith's teachings on the nature of "endless" and "eternal" punishment.
Question: Is there more than one state of "hell"?
The Bible supports the concept that there are two different states of "hell"
John 5:29 states that both the righteous and the wicked will be resurrected:
And shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
Since both the righteous and wicked will be resurrected, there are two states that can be described as "hell" in the scriptures.  1. The temporary condition of the wicked between physical death and resurrection. 2. The never-ending state of the wicked after resurrection and judgment.
The Bible teaches the concept of a redemption from a temporary "hell" through Christ's atonement
Support for this concept of a redemption from the temporary "hell" as the result of Christ's atonement may be obtained from the Bible. For example, David is promised that his soul will not be left "in hell:"
For thou wilt not leave my soul in hell; neither wilt thou suffer thine Holy One to see corruption.
Isaiah also alludes to a redemption of the "prisoners:"
Thus saith the Lord, In an acceptable time have I heard thee, and in a day of salvation have I helped thee: and I will preserve thee, and give thee for a covenant of the people, to establish the earth, to cause to inherit the desolate heritages;
That thou mayest say to the prisoners, Go forth; to them that are in darkness, Shew yourselves. They shall feed in the ways, and their pastures shall be in all high places.
Question: Is the concept of redemption after this life unique to Mormonism?
The concept that God's mercy applies to those who have died is not unique in Latter-day Saint theology
Pope Pius IX once stated,
Far be it from Us, Venerable Brethren, to presume to establish limits to the divine mercy, which is infinite. 
Anglican Oliver Chase Quick said,
Such universal redemption may be said to be the antecedent purpose of God's atoning work in Christ, and we dare not set limits to what the cross may achieve. 
Rev. G. Frederick Wright states in 1882 in his book An Inquiry Concerning the Relation of Death to Probation,
The grounds upon which the Christian public is advised to abandon the historical belief that man's character for eternity is determined by his conduct before death are twofold
First. That certain passages of Scripture, either directly or by implication, teach that some will have their probation continued after death.
Second. That with the supposition of such a continuance of probation the character of God appears more and merciful. 
Continuing on this subject in 1883, Wright states,
It is, indeed, true that if we collect together in one magazine article an account of the individual Christian teachers who during the eighteen hundred years of the existence of Christianity have expressed themselves in favor of restoration or of some sort of probation after death, the list seems formidable. Even Luther can be quoted as favoring a belief that some of the heathen will have the gospel extended to them after death. 
In 1900, George B. Eager suggested that, "It does not become us to set limits to the grace of God." 
The concept that one could be redeemed after death through Christ's atonement is clearly not unique to Mormonism.
To see citations to the critical sources for these claims, click here
- John L. Clark, "Painting Out the Messiah: The Theologies of Dissidents," Journal of Book of Mormon Studies 11/1 (2002): 16–27. off-site wiki
- Arthur R. Bassett, "The Shepherd and His Other Sheep," Ensign (Feb. 1978), 53.
- H. Donl Peterson, "I Have a Question: What is the meaning of the Book of Mormon scriptures on eternal hell for the wicked?," Ensign (April 1986), 36–38.
- Pope Pius IX, Singulari Quadam (1854)
- Oliver Chase Quick, Doctrines of the Creed — Their Basis in Scripture and Their Meaning to Day, p. 260.
- George Frederick Wright, An Inquiry Concerning the Relation of Death to Probation, (Boston: Congregational Publishing Society, 1882), p. 22.
- Rev. G. Frederick Wright, “The Practical Bearings of our belief concerning the Relation of Death to Probation,” Bibliotheca Sacra 40 (1883): 694-713, at page 696-7.
- George B. Eager, "Are the Heathen Lost Without the Gospel?", The Homiletic Review 40 (Oct 1900): 352-5; 355.
- Search for the Truth DVD:What is Hell?
- Barry R. Bickmore, The Tanners on the Hereafter: A Case Study in "Studied Ignorance"