Question: What do the scriptures say about the gathering of Israel?
Answer: These are two questions: (1) who do the scriptures define as Israel? And (2) what do they say about Israel’s gathering?
In the context of “gathering” Israel, it is “the house of Israel” that is gathered and the timeframe is the end of the world. That is when the prophecies of Isaiah are fulfilled, which includes God’s destruction of the wicked in the “Day of the Lord” and the restoration of all the house of Israel.
Isaiah and Book of Mormon prophets identify the house of Israel as Israel’s natural lineages (1 Nephi 10:14)—the Jews, Ten Tribes, and Nephites/Lamanites of today (1 Nephi 19:13–17; 2 Nephi 29:13–14; 3 Nephi 16:4–7). Those who gather them out of a worldwide destruction are the spiritual kings and queens of the Gentiles (Isaiah 49:22–23; 60:3–4; 1 Nephi 21:22–23). These are descendants of Ephraim who assimilated into the Gentiles and among whom the gospel was restored through the prophet Joseph Smith. Within Isaiah’s spiritual hierarchy of people, these spiritual kings and queens ultimately attain seraph status, Isaiah’s equivalent of translated beings.
House of Israel peoples who are gathered before the Lord comes on earth to reign are his “elect” (Matthew 24:31; Doctrine & Covenants 33:6; Moses 7:61–62). These are members of the Church of the Firstborn (Doctrine & Covenants 77:11). The ones who gather them are additionally called “the fulness of the Gentiles”—an expression referencing Ephraim’s descendants as in Jacob’s patriarchal blessing of the two sons of Joseph (Genesis 48:19; Romans 11:23–26; 1 Nephi 15:13; 3 Nephi 16:4); God’s “servants” who graft in the natural branches of the olive tree (Jacob 5:61–72); the 144,000 servants of God who are appointed over the twelve tribes of Israel following the type of Jesus’ twelve apostles (Revelation 7:1–8; cf. Matthew 19:29; 1 Nephi 12:9); the Lord’s watchmen (Isaiah 52:8; 62:6); and saviors on Mount Zion (Obadiah 1:21; Revelation 14:1–5).
The house of Israel’s gathering is initiated by God’s end-time servant David (Isaiah 49:5–12; 55:3–5; Ezekiel 34:1–24; 37:15–28), also known as God’s “arm” who is bared (Isaiah 51:9–11; 52:10, 13–15; 1 Nephi 22:10–12; 2 Nephi 8:9–11; 3 Nephi 20:29–46) at the time the great and abominable church makes war on the saints and covenant people of the Lord (1 Nephi 14:9–17; 22:13–29). The house of Israel’s gathering takes the form of a new exodus to Zion from the four directions of the earth (Isaiah 11:10–16; 27:12–13; 43:5–6; 48:20–21; 49:5–12; 1 Nephi 20:21–21; 21:5–12) “at the time of the restoration” when the two prophets are “raised up to the Jewish nation” (Revelation 11:3–12; Doctrine & Covenants 77:15; 1 Nephi 15:19–20; 2 Nephi 9:2).