2 Nephi 28:1 - 28:5

2 Nephi 28:1 And now, behold, my brethren, I have spoken unto you, according as the Spirit hath constrained me; wherefore, I know that they must surely come to pass.

Nephi tells us that what he has said, he has a personal testimony that these prophecies will happen in the future when he says that will.

2 Nephi 28:2 And the things which shall be written out of the book shall be of great worth unto the children of men, and especially unto our seed, which is a remnant of the house of Israel.

The book he spoke of (The Book of Mormon, I guess he does not know the name by which it will be called) will be so influential that everyone who accepts it will not place a value not it. It will of immeasurable value and worth because of its precepts to all men of the world. It will be especially influential to those who are of the house of Israel.

2 Nephi 28:3 For it shall come to pass in that day that the churches which are built up, and not unto the Lord, when the one shall say unto the other: Behold, I, I am the Lord’s; and the others shall say: I, I am the Lord’s; and thus shall every one say that hath built up churches, and not unto the Lord—

For in the day it will be published, it will find itself in the midst of the various churches of the world competing among each other for converts. They will all say they have the truth and know the correct doctrines of God. However, the building up of these churches will be the for the purpose of making men rich and not for the bring the gospel to the world and not doing so for money.

2 Nephi 28:4 And they shall contend one with another; and their priests shall contend one with another, and they shall teach with their learning, and deny the Holy Ghost, which giveth utterance.

And these various churches will compete with each other for membership. In doing so there will be contention and debate between denominations. Because they do not have the gospel they will teach their own precepts. And in teaching their own precepts they will have had to regarded their own precepts as better than what the Holy Ghost would inspire them to have.

2 Nephi 28:5 And they deny the power of God, the Holy One of Israel; and they say unto the people: Hearken unto us, and hear ye our precept; for behold there is no God today, for the Lord and the Redeemer hath done his work, and he hath given his power unto men;

And since these churches are not listening to the Holy Ghost, they are turning their backs on the power that God could give them and giving up the chance to have the priesthood to perform His works with His sanction. In addition, some are saying that God has quite talking to us and we are on our own. He has given us all we need to know in the scriptures and we can figure it out from here.