We have heretofore identified the Jews as both the nationals of the kingdom of Judah and as their lineal descendants, all this without reference to tribal affiliation. And we have said, within this usage of terms, that all other people are Gentiles, including the lost and scattered remnants of the kingdom of Israel in whose veins the precious blood of him whose name was Israel does in fact flow. Thus Joseph Smith, of the tribe of Ephraim, the chief and foremost tribe of Israel itself, was the Gentile by whose hand the Book of Mormon came forth, and the members of The Church of Jesus Christ of Latter-day Saints, who have the gospel and who are of Israel by blood descent, are the Gentiles who carry salvation to the Lamanites and to the Jews.
It is to those who are not Jews that the Lord promised to give his gospel first in the last days. “In the latter days, when our seed”—now known as Lamanites—”shall have dwindled in unbelief, yea, for the space of many years,” Nephi said, “and many generations after the Messiah shall be manifested in body unto the children of men, then”—and this is to be in the glorious age of restoration in which we now live—”then shall the fulness of the gospel of the Messiah come unto the Gentiles, [the Latter-day church] and from the Gentiles unto the remnant of our seed.” This gospel shall come to them “by way of the Gentiles.” Why? “That the Lord may show his power unto the Gentiles,” Nephi continues, “for the very cause that he shall be rejected of the Jews, or of the house of Israel.” (1 Ne. 15:13-17.)
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We are those Gentiles of whom Nephi speaks. We have received in this age of restoration the fulness of the everlasting gospel. It is now beginning to go from us to the Lamanites and to the Jews. But the great day of the Lamanites and the great day of the Jews both lie ahead. In the full and true sense of the word, the day of their worldwide glory, the day of the triumph and glory of both the Lamanites and the Jews, in all nations—that day will be millennial.
~Bruce R. McConkie
from Millennial Messiah, p 233,238