The scriptures usually divide up mankind's afterlife into two possibilities: heaven and hell. One is a far better reward than we can imagine, the other is a far worse punishment than we can imagine. Modern revelation expands on this, showing that even Hell has an end for everyone except the sons of perdition.
Christ states four times in the doctrine and covenants that his word is quick and powerful, sharper than a two edged sword, to the dividing asunder of both joints and marrow. We don't use swords, but when Ammon cut off many robber's arms, Lamoni decided that Ammon must be more than human. A sword doesn't normally cut through joints and marrow. God's word is sharper than a two edged sword.
Christ's word divides truth from error. it divides right from wrong. It divides the wicked from the righteous. It often divides things into two diametrically opposed alternatives.
The entire chapter of Leviticus 26 is a rather striking example of this. The first part of the chapter is a list of commandments and the blessings Israel will get for keeping them. A small sample is:
Leviticus 26:4 Then I will give you rain in due season, and the land shall yield her increase, and the trees of the field shall yield their fruit.
5 And your threshing shall reach unto the vintage, and the vintage shall reach unto the sowing time: and ye shall eat your bread to the full, and dwell in your land safely.
6 And I will give peace in the land, and ye shall lie down, and none shall make you afraid: and I will rid evil beasts out of the land, neither shall the sword go through your land.
12 And I will walk among you, and will be your God, and ye shall be my people.
These are the promises to them for being righteous.
Then there is a transition:
Levitcus 26:14 But if ye will not hearken unto me, and will not do all these commandments;
15 And if ye shall despise my statutes, or if your soul abhor my judgments, so that ye will not do all my commandments, but that ye break my covenant:
And the rest of the chapter is what the Lord promises to do to those who are not obedient. A sample is:
Leviticus 26:16 I also will do this unto you; I will even appoint over you terror, consumption, and the burning ague, that shall consume the eyes, and cause sorrow of heart: and ye shall sow your seed in vain, for your enemies shall eat it.
17 And I will set my face against you, and ye shall be slain before your enemies: they that hate you shall reign over you; and ye shall flee when none pursueth you.
18 And if ye will not yet for all this hearken unto me, then I will punish you seven times more for your sins.
19 And I will break the pride of your power; and I will make your heaven as iron, and your earth as brass:
22 I will also send wild beasts among you, which shall rob you of your children, and destroy your cattle, and make you few in number; and your high ways shall be desolate.
23 And if ye will not be reformed by me by these things, but will walk contrary unto me;
24 Then will I also walk contrary unto you, and will punish you yet seven times for your sins.
27 And if ye will not for all this hearken unto me, but walk contrary unto me;
28 Then I will walk contrary unto you also in fury; and I, even I, will chastise you seven times for your sins.
29 And ye shall eat the flesh of your sons, and the flesh of your daughters shall ye eat.
30 And I will destroy your high places, and cut down your images, and cast your carcases upon the carcases of your idols, and my soul shall abhor you.
This is quite the dichotomy. But it should be no surprise that this is the dichotomy in mortality that the Lord offered to his covenant people. It is not particularly different than offering the dichotomy of heaven and hell to them in the afterlife. It is the same being that offers us this dichotomy in mortality
We actually see the same thing in the New Testament. To those who were penitent and willing to repent and come unto him, Christ was incredibly tender and merciful. To those who were rebellious, such as the Pharisees, he frequently embarrassed them, and frankly condemned them.
JST Matt 23:15 Woe unto you, scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte, and when he is made, ye make him twofold more the child of hell than he was before, like unto yourselves.
33 Ye serpents, ye generation of vipers, how can ye escape the damnation of hell?
Twice in his life he made a cat of nine tails (a whip with many thongs) and used it to forcibly drive the money changers from the temple. Let us not doubt that separating these people from their money, turning over their tables, and forcibly driving them out of the temple was a brutal affair. That is because Christ was the same God in the new testament that he was in the old testament.
When people read the old and new testament they feel like the God of the old testament is a different being than the tender Savior. But it is not God that is different in the two. In the new testament we are getting many personal accounts of Christ's dealings with those who were penitent, who were willing turn from their sins, to exercise faith in him and be healed. By contrast in the old testament we are getting many accounts of Christ dealing with a rebellious Israel. The difference is not in Christ. The difference is in who we are hearing about his dealings with.
The Book of Mormon account nicely hits both groups. We see Christ's dealings with the wicked and rebellious, as well as his dealings with the penitent, the repentant, and the faithful.
It is the same dichotomy as heaven and hell. To the penitent and to the faithful, Christ was incredibly tender and merciful as a whole. Yes, at times he offered chastisement and correction, but his dealings with them are tender, merciful and kind according to their obedience.
But he visited the wicked with misery and destruction.
This is the great dichotomy offered to us. We must not buy into the modern idea that tenderness and gentleness are offered by God to the wicked and rebellious except on the terms that he always offers them - repentance and turning unto him.
He is the same God that offers to his children the possibility of happiness beyond their ability to conceive if they are righteous, and suffering beyond their ability to conceive if they are wicked.
Yes, hell has an end, but observing the description in the scriptures, the end of hell for the wicked does not come about before their repentance. It is not particularly different than the terms by which mercy is offered to them here.
He really is the same God yesterday, today, and forever.