What then is to become of the Gentiles of the latter days? If the plan of the Lord is to "bring the fulness of my gospel from among them," (the Gentiles) (3Nephi 16: 10) and to "then... remember my covenant which I have made unto my people, O house of Israel, and I will bring my gospel unto them," (the remnant of Nephi's seed) (3Nephi 16: 11) what is to become of the Gentiles and the restoration work completed by Joseph Smith and the Gentiles? We have already seen that the restoration work of the Gentiles was fulfillment of Book of Mormon prophecy. The bringing forth of the Book of Mormon and other scripture by the Gentiles was in large part done so that the truth and those sacred records could be transmitted to those of the house of Israel, especially the remnant of Israel whose fathers made the Book of Mormon record. (1Nephi 10: 14, 1Nephi 13: 39, 1Nephi 15: 13, 2Nephi 28: 2, 2Nephi 30: 3, 3Nephi 21: 2-3 among many others)
In a revelation given to Joseph Smith through the Urim and Thummim in July 1828, the Lord made clear His plan concerning the contents of the record of the Book of Mormon. He said,
"...my work shall go forth, for inasmuch as the knowledge of a Savior has come unto the world, through the testimony of the Jews, (the Bible) even so shall the knowledge of a Savior come unto my people—And to the Nephites, and the Jacobites, and the Josephites, and the Zoramites, through the testimony of their fathers—And this testimony shall come to the knowledge of the Lamanites, and the Lemuelites, and the Ishmaelites, who dwindled in unbelief because of the iniquity of their fathers, whom the Lord has suffered to destroy their brethren the Nephites, because of their iniquities and their abominations. And for this very purpose are these plates preserved, which contain these records—that the promises of the Lord might be fulfilled, which he made to his people; And that the Lamanites might come to the knowledge of their fathers, and that they might know the promises of the Lord, and that they may believe the gospel and rely upon the merits of Jesus Christ, and be glorified through faith in his name, and that through their repentance they might be saved. Amen." (D&C 3: 16-29)
"For this very purpose" the record on the plates translated by Joseph was preserved by the Lord. This revelation to the Gentile prophet Joseph, clarifies and restates the Lord's declaration to the Nephites that after he has brought the fullness of His gospel from among the Gentiles, (3Nephi 16: 10) he will then "remember my covenant which I have made unto my people, O house of Israel, and I will bring my gospel unto them," (3Nephi 16: 11) This then, is the very prophetic purpose, according to the Lord, of the Book of Mormon.
The work of the latter day Gentiles, according to Book of Mormon prophecy, has set the stage for the fulfillment of all of God's words concerning "His people." (1Nephi 21: 1, 3Nephi 16: 8-9, 11, 13-15, 3Nephi 20: 21-22 and many others) As often as the Lord uses the phrase "my people," it is never used to describe the Gentiles. The focus of the Lord's plan after the restoration of truth by the Gentiles, shifts to the "very purpose" for which the Book of Mormon was preserved and brought forth. That focus of His plan will no longer be the Gentiles, it will be instead, "His people," scattered Israel.
There is no part of any Book of Mormon prophecy by Lehi, Nephi, Jacob, Isaiah, Mormon, Moroni, or the Lord Jesus Christ, (or any other) that speaks about the successful perpetuation of any latter day institution established by the Gentiles. Quite strikingly to the contrary, the Book of Mormon prophets continually, and repeatedly, point out the failures of the Gentiles in the latter days. Here are just a few of the numerous examples. And, no, these words are not meant by the prophets to mean any "other people." Despite our undying inclination to attribute these unsavory observations of the prophets to those poor "other churches" and people who do not belong to the "true church," the warnings are in fact for, and directed to, the latter day Gentile church. Consider, how much like the Lord's own words to the Gentiles in the final verse of 3Nephi, these words of the other Book of Mormon prophets are. The message is perfectly consistent throughout because the message is the Lord's.
"Because of pride, and because of false teachers, and false doctrine, their churches have become corrupted, and their churches are lifted up; because of pride they are puffed up. They rob the poor because of their fine sanctuaries; they rob the poor because of their fine clothing; and they persecute the meek and the poor in heart, because in their pride they are puffed up. They wear stiff necks and high heads; yea, and because of pride, and wickedness, and abominations, and whoredoms, they have all gone astray save it be a few, who are the humble followers of Christ; nevertheless, they are led, that in many instances they do err because they are taught by the precepts of men." (2Nephi 28: 12-14)
"Cursed is he that putteth his trust in man, or maketh flesh his arm, or shall hearken unto the precepts of men, save their precepts shall be given by the power of the Holy Ghost. Wo be unto the Gentiles, saith the Lord God of Hosts! For notwithstanding I shall lengthen out mine arm unto them from day to day, they will deny me; nevertheless, I will be merciful unto them, saith the Lord God, if they will repent and come unto me; for mine arm is lengthened out all the day long, saith the Lord God of Hosts." (2Nephi 28: 31-32)
"And I say unto you, that if the Gentiles do not repent after the blessing which they shall receive, after they have scattered my people—Then shall ye, who are a remnant of the house of Jacob, go forth among them; and ye shall be in the midst of them who shall be many; and ye shall be among them as a lion among the beasts of the forest, and as a young lion among the flocks of sheep, who, if he goeth through both treadeth down and teareth in pieces, and none can deliver." (3 Nephi 20: 15-16)
"And then, O ye Gentiles, how can ye stand before the power of God, except ye shall repent and turn from your evil ways? Know ye not that ye are in the hands of God? Know ye not that he hath all power, and at his great command the earth shall be rolled together as a scroll? Therefore, repent ye, and humble yourselves before him, lest he shall come out in justice against you—lest a remnant of the seed of Jacob shall go forth among you as a lion, and tear you in pieces, and there is none to deliver." (Mormon 5: 22-24)
"O ye wicked and perverse and stiffnecked people, why have ye built up churches unto yourselves to get gain? Why have ye transfigured the holy word of God, that ye might bring damnation upon your souls? Behold, look ye unto the revelations of God; for behold, the time cometh at that day when all these things must be fulfilled.
Behold, the Lord hath shown unto me great and marvelous things concerning that which must shortly come, at that day when these things shall come forth among you. Behold, I speak unto you as if ye were present, and yet ye are not. But behold, Jesus Christ hath shown you unto me, and I know your doing. And I know that ye do walk in the pride of your hearts; and there are none save a few only who do not lift themselves up in the pride of their hearts, unto the wearing of very fine apparel, unto envying, and strifes, and malice, and persecutions, and all manner of iniquities; and your churches, yea, even every one, have become polluted because of the pride of your hearts. For behold, ye do love money, and your substance, and your fine apparel, and the adorning of your churches, more than ye love the poor and the needy, the sick and the afflicted. O ye pollutions, ye hypocrites, ye teachers, who sell yourselves for that which will canker, why have ye polluted the holy church of God? Why are ye ashamed to take upon you the name of Christ? Why do ye not think that greater is the value of an endless happiness than that misery which never dies—because of the praise of the world? Why do ye adorn yourselves with that which hath no life, and yet suffer the hungry, and the needy, and the naked, and the sick and the afflicted to pass by you, and notice them not?" (Mormon 8: 33-39)
The final words of the book containing the record of the ministry of the Lord Jesus to the Nephites:
"Turn, all ye Gentiles, from your wicked ways; and repent of your evil doings, of your lyings and deceivings, and of your whoredoms, and of your secret abominations, and your idolatries, and of your murders, and your priestcrafts, and your envyings, and your strifes, and from all your wickedness and abominations, and come unto me, and be baptized in my name, that ye may receive a remission of your sins, and be filled with the Holy Ghost, that ye may be numbered with my people who are of the house of Israel." (3Nephi 30: 2)