3 Nephi 12:13 Verily, verily I say unto you, I give unto you to be the salt of the earth, but if the salt shall lose its savor, wherewith shall the earth be salted? The salt shall be thenceforth good for nothing but to be cast out and to be trodden under foot of men.That's the covenant in a nutshell.
You will be agreeing to do specific things, and those specific things are contained in 3 Nephi chapters 12-14, noting also chapter 15 verse 1. If you do them without fail, then you are the salt of the earth, a savior of men. He means it.
If you shall fail to do those specific things, you shall be trodden down as is prophesied.
3 Nephi 16:10-15If, as I am informed, the LDS Church never received the Book of Mormon by covenant, then they rejected the fulness of the gospel. The LDS apparently never entered into the covenant to be able to break it - to be as corrupted and useless salt, cast out and trodden underfoot by the remnant of Jacob. That future potential failure belongs to Gentiles that come after the LDS and receive the Book of Mormon by covenant and do not perform unto the Lord their oath. Like, say, the Restorationist Gentiles, who are right now proposing to receive the Book of Mormon by covenant.
10 And thus commandeth the Father that I should say unto you: At that day when the Gentiles shall sin against my gospel, and shall reject the fulness of my gospel, and shall be lifted up in the pride of their hearts above all nations, and above all the people of the whole earth, and shall be filled with all manner of lyings, and of deceits, and of mischiefs, and all manner of hypocrisy, and murders, and priestcrafts, and whoredoms, and of secret abominations; and if they shall do all those things, and shall reject the fulness of my gospel, behold, saith the Father, I will bring the fulness of my gospel from among them.
11 And then will I remember my covenant which I have made unto my people, O house of Israel, and I will bring my gospel unto them.
12 And I will show unto thee, O house of Israel, that the Gentiles shall not have power over you; but I will remember my covenant unto you, O house of Israel, and ye shall come unto the knowledge of the fulness of my gospel.
13 But if the Gentiles will repent and return unto me, saith the Father, behold they shall be numbered among my people, O house of Israel.
14 And I will not suffer my people, who are of the house of Israel, to go through among them, and tread them down, saith the Father.
15 But if they will not turn unto me, and hearken unto my voice, I will suffer them, yea, I will suffer my people, O house of Israel, that they shall go through among them, and shall tread them down, and they shall be as salt that hath lost its savor, which is thenceforth good for nothing but to be cast out, and to be trodden under foot of my people, O house of Israel.
Did you read 3 Nephi chapters 12 through 14, noting chapter 15 verse 1? Do you understand what it is you are proposing to bind yourself into doing? And, if you do, isn't it wise to start the practice of doing those things today, even right now?
Are you giving to every man that asks?
Are you lending to all comers, hoping that you will not be paid back?
Are you storing up money or food or goods for yourself in this world, or are you giving your excess stores of money or food or goods to the poor?
And so on.
If you didn't read 3 Nephi chapters 12-14, noting chapter 15 verse 1, now would be a great time to go and read it. You have it before you, both life and death; as Moses set it before Israel, so it is set before you.