Nephi notes that the Spirit will manifest Jesus to the Gentiles, as well as to the Jews. The Gentiles may also experience mighty miracles, signs, and wonders, according to their faith. Nephi, as a Jew and a participant in the covenant from birth, certainly understands that Yahweh has manifested his power to Israel through miracles, signs, and wonders. This spiritual history is the heritage of the covenant.
Nephi tells the Gentiles that they, too, may receive these same blessings in the future, although their noncovenant status excluded them in the past. The Spirit will, in the future, work through faith rather than covenant.
This is an important statement, not only for Gentiles in the future but perhaps also for the social conditions Nephi was dealing with. (See commentary accompanying 2 Nephi 26:33 below.)