There are three things in the book of Moses that are said to be at the beginning of the world and at the end of the world; three things that will remain for the entire human race’s existence. These three things come from Enoch’s preaching: he is explaining how God set things up for Adam and how that affects the rest of us. (Kind of cool that he knew Adam personally, too.) Here are the three things:
1) THE GOSPEL (Moses 5:58-59; 5:14-15):
14 And the Lord God called upon men by the Holy Ghost everywhere and commanded them that they should repent;
15 And as many as believed in the Son, and repented of their sins, should be saved; and as many as believed not and repented not, should be damned; and the words went forth out of the mouth of God in a firm decree; wherefore they must be fulfilled.
58 And thus the Gospel began to be preached, from the beginning, being declared by holy angels sent forth from the presence of God, and by his own voice, and by the gift of the Holy Ghost.
59 And thus all things were confirmed unto Adam, by an holy ordinance, and the Gospel preached, and a decree sent forth, that it should be in the world, until the end thereof; and thus it was. Amen.
2) THE PRIESTHOOD (Moses 6:7):
7 Now this same Priesthood, which was in the beginning, shall be in the end of the world also.
3) A CHOSEN SEED (Moses 6:2, but more clear in D&C 107:42):
2 And Adam knew his wife again, and she bare a son, and he called his name Seth. And Adam glorified the name of God; for he said: God hath appointed me another seed, instead of Abel, whom Cain slew.
D&C 107:42 From Adam to Seth, who was ordained by Adam at the age of sixty-nine years, and was blessed by him three years previous to his (Adam’s) death, and received the promise of God by his father, that his posterity should be the chosen of the Lord, and that they should be preserved unto the end of the earth;
And I think the idea is that these three things go together: There is a chosen seed, a lineage that God will preserve, which is entrusted with the priesthood and the preaching of the gospel. When Adam makes his declaration that the priesthood will remain in Moses 6:7, it is right after he has both a son and a grandson who believe, and it says that “And then began these men to call upon the name of the Lord, and the Lord blessed them” (v.4). After Moses 6 lists Adam’s righteous sons down to Enoch, it says, “And this is the genealogy of the sons of Adam, who was the son of God, with whom God, himself, conversed. And they were preachers of righteousness, and spake and prophesied, and called upon all men, everywhere, to repent; and faith was taught unto the children of men” (v.22-23).
I think this promise of a chosen seed, which is entrusted with the priesthood and the preaching of the gospel, is the precursor to the Abrahamic Covenant. It is given to Adam and then renewed with Seth, Enos, Cainan, Mahalaleel, Jared, Enoch, Methuselah, Lamech, and Noah (see D&C 107:40-57).
Then after Noah, I have a hard time tracing the chosen seed until we get to Abraham. Perhaps that’s one reason we associate it with Abraham: it was dormant and he is the one through whom it was revived?
Abraham’s fathers rejected their role as a chosen seed which had the priesthood and preached the gospel. Ironically, they were won over by the idea that the Egyptians had the right priesthood and started worshiping their idols! Abraham has the book that explains Adam’s promises and how the genealogy of the priesthood as worked (Abraham 1:31). He knows about the promises given to Adam, and he decided he wants to be the next step in the chain: he wants to be a father through whom the chosen seed, and the promise of priesthood and preaching, can keep going.
2 And, finding there was greater happiness and peace and rest for me, I sought for the blessings of the fathers, and the right whereunto I should be ordained to administer the same; having been myself a follower of righteousness, desiring also to be one who possessed great knowledge, and to be a greater follower of righteousness, and to possess a greater knowledge, and to be a father of many nations, a prince of peace, and desiring to receive instructions, and to keep the commandments of God, I became a rightful heir, a High Priest, holding the right belonging to the fathers.
3 It was conferred upon me from the fathers; it came down from the fathers, from the beginning of time, yea, even from the beginning, or before the foundation of the earth, down to the present time, even the right of the firstborn, or the first man, who is Adam, or first father, through the fathers unto me.
4 I sought for mine appointment unto the Priesthood according to the appointment of God unto the fathers concerning the seed.
I think though that Abraham got more than he asked for: he also gets a promise that has his literal seed preaches the gospel, anyone who believes will be counted as Abraham’s adopted seed. Why this promise? I don’t know of course, but I think the reason stems from the fact that only the chosen seed has been called on to preach the gospel and hold the priesthood. By including all believers in his family — as members of the chosen seed, as it were — then eventually hundreds and thousands of people can be preaching the gospel with the priesthood ordinances and thereby “shall all the families of the earth be blessed, even with the blessings of the Gospel, which are the blessings of salvation, even of life eternal.” As I understand D&C 107, the right to the priesthood continues only through the faithful members of the literal chosen seed, but as others are adopted in, those may also be asked to help in the work of preaching the gospel and preparing people to see God again. With Abraham, what changes is that many many others are asked to assist in the same work that Adam, Seth, Enos, Enoch, Noah, etc. were called to do.
In addition, the chosen seed has the promise that it won’t die out. Even when the chosen seed is unrighteous (like Abraham’s fathers), they aren’t destroyed so that one of their descendants can pick back up and keep preaching. This promise becomes more interesting when now there is a whole group of people considered Abraham’s chosen seed. This promise goes to Isaac and Jacob, and with Jacob’s 12 sons we have a whole tribe who is blessed as a chosen people. Isaiah is very clear that God will always remember Israel and that they will never be destroyed; Lehi’s people are a testament to this. Even when everyone’s wicked and the Lamanites wipe out the Nephites, there is still the remnant of the Lamanites that still remains and will remain. Nephi knows this, which is why he writes his book and teaches others to write, why it is buried in the ground, and why it comes in the latter-days to be given back to that remnant of Israel: they don’t know it, but they are the chosen seed, charged with holding the priesthood and preaching the gospel. Since they don’t know it, it is up to Gentiles to teach them until they do know it. It’s God’s “tender mercy” to the Gentiles to let them become involved.
And so that’s where the Abrahamic Covenant is today. The Church is filled with those born “as if” part of the chosen seed of Abraham, and thereby also charged with preaching the gospel and allowing the priesthood ordinances to prepare them to see God again. A big part of this is the temple, both in how we become sealed up into Abraham’s family “as if” we had been born his literal chosen seed, and how we prepare ourselves and others to be ready to literally see the face of God.