Helaman 12

As we see that again after being blessed with prosperity, the Nephites and Lamanites in such a short time, begin to turn to those same old problems of power and pride, materialism, and immorality. Mormon, in his great wisdom, then comments -

"...thus we see that except the Lord doth chasten his people with many afflictions, yea, except he doth visit them with death and with terror, and with famine and with all manner of pestilence, they will not remember him.
4 O how foolish, and how vain, and how evil, and devilish, and how quick to do iniquity, and how slow to do good, are the children of men; yea, how quick to hearken unto the words of the evil one, and to set their hearts upon the vain things of the world!
5 Yea, how quick to be lifted up in pride; yea, how quick to boast, and do all manner of that which is iniquity; and how slow are they to remember the Lord their God, and to give ear unto his counsels, yea, how slow to walk in wisdom's paths!" (Book of Mormon | Helaman 12:3 - 5)

Why?

"...they do not desire that the Lord their God, who hath created them, should rule and reign over them; notwithstanding his great goodness and his mercy towards them, they do set at naught his counsels, and they will not that he should be their guide." (Book of Mormon | Helaman 12:6)

The next few verses (8-18) substantiates my personal believe (don't anyone accept this as accepted Church doctrine)that this earth has an eternal purpose and is a living (spiritally and physically) entity as the earth is an obedient and faithful entity to anything commanded of it.

Mormon than makes it clear that the Lord will be merciful and will forgive all men -

"...for it shall be unto him that will do iniquity, and he cannot be saved; therefore, for this cause, that men might be saved, hath repentance been declared.
23 Therefore, blessed are they who will repent and hearken unto the voice of the Lord their God; for these are they that shall be saved.
24 And may God grant, in his great fulness, that men might be brought unto repentance and good works, that they might be restored unto grace for grace, according to their works." (Book of Mormon | Helaman 12:22 - 24)

For Mormon desires and admits -

"...I would that all men might be saved. But we read that in the great and last day there are some who shall be cast out, yea, who shall be cast off from the presence of the Lord;
26 Yea, who shall be consigned to a state of endless misery, fulfilling the words which say: They that have done good shall have everlasting life; and they that have done evil shall have everlasting damnation. And thus it is." (Book of Mormon | Helaman 12:25 - 26)