What Was The Great And Terrible Gulf In Lehi’s Dream?

And the large and spacious building, which thy father saw, is vain imaginations and the pride of the children of men. And a great and a terrible gulf divideth them; yea, even the word of the justice of the Eternal God, and the Messiah who is the Lamb of God, of whom the Holy Ghost beareth record, from the beginning of the world until this time, and from this time henceforth and forever. (1 Nephi 12:18)

The justice of God cannot allow the wicked and righteous to receive the same reward. This seems simple enough, however Alma's son Corianton had trouble with this concept, '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' (Alma 42:1). Alma goes on to show his son that it is injustice if the sinner is not punished, 'What, do ye suppose that mercy can rob justice?...whosoever will come [unto God] may come and partake of the waters of life freely; and whosoever will not come the same is not compelled to come; but in the last day it shall be restored unto him according to his deeds. If he has desired to do evil and has not repented in his days, behold, evil shall be done unto him, according to the restoration of God' (Alma 42:25-28).

The D&C teaches that the individual must be able to abide the law of the kingdom he/she enters, 'For he who is not able to abide the law of a celestial kingdom cannot abide a celestial glory' (D&C 88:22). A corollary to this principle is taught by Moroni, 'Do ye suppose that ye could be happy to dwell with that holy Being, when your souls are racked with a consciousness of guilt that ye have ever abused his laws? Behold, I say unto you that ye would be more miserable to dwell with a holy and just God, under a consciousness of your filthiness before him, than ye would to dwell with the damned souls in hell' (Mormon 9:3-4).

Therefore, the justice of God is actually merciful in requiring that the righteous and wicked be separated. In the parable of the rich man and Lazarus, this same gulf is described separating those in Spirit Prison from those in Spirit Paradise, 'between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence' (Luke 16:26).

Hugh Nibley
"...'a great and terrible gulf divideth them.' There it is again. It is a figure of speech, an image. Nothing could better describe it; there is a great and terrible gulf between two different ways of living. There is nothing in common between them at all. You can't breach it...." (Teachings of the Book of Mormon--Semester 1: Transcripts of Lectures Presented to an Honors Book of Mormon Class at Brigham Young University, 1988-1990, p. 195)