2 Nephi 9

The prophet Jacob must have been a very obedient, diligent, and special person. Nephi must have been very impressed with him as he wrote these words of his brother -

"Behold, my beloved brethren, I, Jacob, having been called of God, and ordained after the manner of his holy order, and having been consecrated by my brother Nephi, unto whom ye look as a king or a protector, and on whom ye depend for safety, behold ye know that I have spoken unto you exceedingly many things.
3 Nevertheless, I speak unto you again; for I am desirous for the welfare of your souls. Yea, mine anxiety is great for you; and ye yourselves know that it ever has been. For I have exhorted you with all diligence; and I have taught you the words of my father; and I have spoken unto you concerning all things which are written, from the creation of the world.
4 And now, behold, I would speak unto you concerning things which are, and which are to come; wherefore, I will read you the words of Isaiah. And they are the words which my brother has desired that I should speak unto you." (Book of Mormon 2 Nephi 6:2 - 4)

He speaks of an -

"...awful monster; yea, that monster, death and hell, which I call the death of the body, and also the death of the spirit." (Book of Mormon 2 Nephi 9:10)

Of the monster, death and hell, he explains -

"For as death hath passed upon all men, to fulfil the merciful plan of the great Creator, there must needs be a power of resurrection..." (Book of Mormon 2 Nephi 9:6)

"...Wherefore, it must needs be an infinite atonement..." (Book of Mormon 2 Nephi 9:7)

Without this "power of the resurrection" Jacob teaches the consequences -

"O the wisdom of God, his mercy and grace! For behold, if the flesh should rise no more our spirits must become subject to that angel who fell from before the presence of the Eternal God, and became the devil, to rise no more.
9 And our spirits must have become like unto him, and we become devils, angels to a devil, to be shut out from the presence of our God, and to remain with the father of lies, in misery, like unto himself; yea, to that being who beguiled our first parents, who transformeth himself nigh unto an angel of light, and stirreth up the children of men unto secret combinations of murder and all manner of secret works of darkness.
10 O how great the goodness of our God, who prepareth a way for our escape from the grasp of this awful monster..." (Book of Mormon 2 Nephi 9:8 - 10)

By the power of the Savior's infinite atonement -

"...this death, of which I have spoken, which is the temporal, shall deliver up its dead; which death is the grave.
12 And this death of which I have spoken, which is the spiritual death, shall deliver up its dead; which spiritual death is hell; wherefore, death and hell must deliver up their dead, and hell must deliver up its captive spirits, and the grave must deliver up its captive bodies, and the bodies and the spirits of men will be restored one to the other; and it is by the power of the resurrection of the Holy One of Israel." (Book of Mormon 2 Nephi 9:11 - 12)

But even though the atonement delivers men for the the awful monster, death and hell, it does not necessarily deliver them from -

"...that lake of fire and brimstone, which is endless torment." (Book of Mormon 2 Nephi 9:19)

"...it shall come to pass that when all men shall have passed from this first death unto life, insomuch as they have become immortal, they must appear before the judgment-seat of the Holy One of Israel; and then cometh the judgment, and then must they be judged according to the holy judgment of God.
16 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." (Book of Mormon 2 Nephi 9:15 - 16)

Of the righteous that are righteous still or -

"...the righteous, the saints of the Holy One of Israel, they who have believed in the Holy One of Israel, they who have endured the crosses of the world, and despised the shame of it, they shall inherit the kingdom of God, which was prepared for them from the foundation of the world, and their joy shall be full forever.
19 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." (Book of Mormon 2 Nephi 9:18 - 19)

"And if they will not repent and believe in his name, and be baptized in his name, and endure to the end, they must be damned; for the Lord God, the Holy One of Israel, has spoken it." (Book of Mormon 2 Nephi 9:24)