Remember that this comes at the end of Nephi’s ministry. He saw the vision of the great and abominable church at the beginning of his journey into the wilderness. There has been over forty years between the time of the earlier visions and the time of this summary of his great teachings. (See 2 Ne. 5: 34.)
Between the time Nephi saw the visions (set out beginning in 1 Nephi 11) and the time of this final instruction, Nephi has had decades to ponder on the things he was shown in vision. He has, in fact, spent those years reflecting constantly upon the visions he received. (2 Ne. 4: 16.) It is foolish to believe that Nephi, Joseph Smith or any prophet understood what they saw the day they saw it. Only time, careful, solemn and ponderous thought can unravel what a person is shown in vision by the Lord. The understanding of a prophet is not static. It unfolds. Joseph’s first impression of the first vision was personal. He thought it was a message to him about himself. By the time he had finished translating the Book of Mormon, organizing the church, and collecting a following, Joseph realized the first vision was not his, but it belonged at a minimum to a larger community of believers. Eventually he would come to see it belonged to the world. The version we have in the Pearl of Great Price reflects that changing understanding. In it he gives the first understanding in what he told his mother the day it happened: He learned that Presbyterianism was not true. (JS-H 1: 20.)
So this statement goes back forty years earlier and Nephi’s vision of the fall of the great whore. This universal false religion will fail. It will “fall.” The “fall” will be “great.” It will “tumble to the earth”-- meaning that it will no longer stand on its own, but will altogether collapse.
The purpose of this great calamity is to bring about repentance. The purposes of God, even in punishment, are to elevate and save others.
Notice the devil’s tool that will be used in opposition to repentance: they will “be stirred up to anger, and perish.” That is, to harden hearts and to blind eyes, anger will be the most effective tool. Rather than being humbled by the fall of the great whore, those who will continue to resist repentance will be angry for the losses. They will lament the loss of what they held so dearly.
This, then, is how the groups break down - For those who repent, the difficulties they encounter bring humility and contrition. For those who refuse to repent, they respond with anger at their trials.
This is the great watershed test. If your set backs in life humble you, then your heart is soft and you are a candidate for repentance. If you become angry, accuse God of causing evil, and refuse to be comforted, you are not a candidate for repentance. Your anger is a tool used to blind you. The one employing the tool is the enemy to your soul.
The trials and difficulties are gifts to stir you up to repentance. That is how you ought to respond. The only way to approach the Lord is through humility. Anything that aids you in becoming humble is good, merciful and just. You should view it as a gift. No matter the difficulty. Christ descended below it all; and none of us are greater than He. (D&C 122: 8.)