Removing the parenthetical asides from this long and complex sentence leaves us with the crucial information as contained in the first and last clauses. After Israel is scattered and persecuted, "the day will come" when they will begin to believe "these things." What are "these things?"
Following Nephi's explanation of the "future history" of Israel and the internal clauses of this sentence that emphasize the mission of the Savior, "these things" encompass Nephi's understanding of the message of Isaiah, which would include the birth and mission of the mortal Messiah as well as the eventual triumphal entry of that Messiah that will see the times of the restoration of Israel to its honored place as God's people.