Nephi says the coming forth of the Book of Mormon will allow this sacred record to be circulated among the Gentiles and then it will reach the remnants of the Lamanites and Nephites. This will allow them to learn about the covenants which the Lord made with their forefathers. Nephi says it will also let them know they are descendants of the Jews. Of course they are also descendants of Ephraim and Manasseh, but Nephi wants them to know that any blessings pronounced upon the Jews who join the Church will also come upon them.