Again a reminder that Nephi's teachings come from an angel. He's not on his own errand in making these things known. I doubt a person of good faith and common sense would ever dare to make declarations as Nephi does unless he had received the message from such a source. Joseph put it this way: "None but fools will trifle with the souls of men. How vain and trifling have been our spirits, our conferences, our councils, our meetings, our private as well as public conversations—too low, too mean, too vulgar, too condescending for the dignified characters of the called and chosen of God, according to the purposes of His will, from before the foundation of the world!" (DHC Vol 3, pp. 295-96.) Nephi was no fool. He wanted us to understand these teachings came from a higher source, and not man's wisdom. Indeed, what man can open up the mysteries that have remained hidden? Either God makes them known or they remain a mystery!
I believe the wisest course would have been for all our teachers, from Joseph till today, to either declare what the Lord and His angels have made known to them or to remain silent. Had that been the practice our libraries would undoubtedly be sparse. But what few books that remained would be the "best books" worthy of study. (D&C 88: 118.) I understand that not all have faith. But teachers do a profound disservice whenever they pontificate about something they do not understand. No-one is an "authority" who has not received intelligence from the Lord or His angels. They are simply trying to be helpful, or seeking to magnify a calling, but they are not on His errand. Alas, the full extent of this problem cannot be known. All those who have spoken in His name, but without His instruction and direction, have indeed taken His name in vain. This will be a great burden for those who have chosen to use His name in violation of a fundamental commandment to the contrary. (Exo. 20: 7.)
The happy news is that "if the Gentiles repent"-- is always a condition for moving forward. We can't get through carrying on our backs the false, vain and foolish traditions men have handed to us. We must lay them down. Unless we do so we wind up exactly at the point when this Dispensation began: suffering under doctrine which consists merely of the commandments of men, having a form of godliness without power. (JS-H 1: 19.)
What must gentiles do to "repent?" All gentiles, including those who have accepted the Restoration and who claim to believe the Book of Mormon... What must they do? To answer that look again carefully at the Lord's condemnation of us:
"And your minds in times past have been darkened because of unbelief, and because you have treated lightly the things you have received— Which vanity and unbelief have brought the whole church under condemnation. And this condemnation resteth upon the children of Zion, even all. And they shall remain under this condemnation until they repent and remember the new covenant, even the Book of Mormon and the former commandments which I have given them, not only to say, but to do according to that which I have written—That they may bring forth fruit meet for their Father’s kingdom; otherwise there remaineth a scourge and judgment to be poured out upon the children of Zion." (D&C 84: 54-58.)
Then Nephi's angel-minister reminds Nephi of two different thoughts: 1) There are covenants with the house of Israel. So they will be remembered. 2) Whoever repents will find things will be well. Nephi was told: "thou also knowest concerning the covenants of the Lord unto the house of Israel; and thou also hast heard that whoso repenteth not must perish." The result is that even though the gentiles are not given a covenant status, they are nonetheless included within the promise that it is well with whoever should repent. Accordingly, if they will repent, the gentiles will not perish but will have eternal life.
How beautiful upon the mountains are the feet of those who declare that God reigneth and will deliver His people. How merciful it is that the Lord God will accept all those as His people who will repent and come unto Him.