1 Nephi 15:18

18 Wherefore, our father hath not spoken of our seed alone, but also of all the house of Israel, pointing to the covenant which should be fulfilled in the latter days; which covenant the Lord made to our father Abraham, saying: In thy seed shall all the kindreds of the earth be blessed.

The Abrahamic Covenant seems like one of those things that is simple on the surface, but there’s more to it when you dig into it. For instance, the covenant was made with Abraham, and we always look to the Jews or the tribes of Israel to be the lineage through which that covenant would be fulfilled. Certainly that is the case, especially considering that Jesus Christ himself is of that line. But there is also the fact that the Gentiles would play a major role, especially in the latter days, in fulfilling the covenant to bless all the kindreds of the earth. So did the Jews give up their privilege to be the ones who would fulfill this covenant? After all, they were scattered, and the ancestors of today’s Jews rejected and even crucified Christ. So for the most part, they are in apostasy and not fulfilling the covenant. Enter the adoption of others into the covenant, the Gentiles. So we see that a spiritual lineage is at least as valid as the blood lineage. Abraham 2:11 (8–11) makes a clear distinction between the literal seed of Abraham, and the covenant seed. Verse ten says that those who “receive this gospel shall be called after [Abraham’s] name, and shall be accounted [his] seed.” There just seems to be more to this covenant than is immediately apparent. But maybe I’m making it more complicated than it needs to be. The simplicity of it is that those who make a covenant with Christ through baptism by the proper authority are in the Abrahamic Covenant and are subject to the responsibilities and blessings of that covenant.