Moroni played a major role in the last three books in the Book of Mormon. As indicated in Morm. 8:1, he finished "the record of my father, Mormon." In finishing that record, Moroni wrote the last two chapters of the small book bearing his father's name.
Moroni was the compiler of the book of Ether, and was the author of the book of Moroni, except for two chapters.Chapters 7 and 8 in the book of Moroni contain teachings of Mormon. Moroni 7 is a synopsis of a sermon Mormon delivered "in the synagogue which they had built for the place of worship" and Moroni 8 is an epistle that Mormon wrote to Moroni.
The sermon in Moroni 7 was directed to those "of the church, that are the peaceable followers of Christ, and that have obtained a sufficient hope by which ye can enter into the rest of the Lord, from this time henceforth until ye shall rest with him in heaven." (Moro. 7:3.)
What does it mean to enter into the "rest of the Lord?" The Book of Mormon Student Manual, produced by the Church Educational System, quotes President Joseph F. Smith:
"To the young man or the young woman who is at a loss to know what to do, among all the various teachings that are extant in the world, I would say: Search the scriptures, seek God in prayer, and then read the doctrines that have been proclaimed by Christ in His sermon on the mount, as found in Matthew, and as reiterated to the ancient saints upon this continent. (See 3 Nephi.) Having studied these splendid standards, and searched deeply the significance of these matchless sentiments, you may defy the philosophies of the world, or any of its ethics to produce their equal. The wisdom of men is not to be compared with them. They the scriptures and doctrines of ChristT lead to the rest of the peaceable followers of Christ, and enable mankind to become perfect as He is perfect.
"No other philosopher has ever said,
Come unto me.' From the beginning of the world until the present time, no other philosopher has ever cried unto the people such words of love, nor guaranteed and declared power within himself to save.Come unto me, all ye that labor and are heavy laden, and I will give you rest,' is His call to all the sons and daughters of men.
"The Latter-day Saints have answered the call, and thousands thereby have found rest and peace surpassing all understanding; and this notwithstanding the outward fiery ordeals, the turmoil and the strife, through which they have passed. They rest in the knowledge that no man could declare or teach such doctrine; it is the truth of God.
"I thank our Father that I have come to a knowledge of this truth, that I know that Jesus is the Christ, in whom alone there is rest and salvation. As God lives, they are deceived who follow men and their philosophies; but happy are they who enter into the rest of the peaceable followers of Christ, obtaining a sufficient hope from this time henceforth until they shall rest with Him in heaven. They depend completely upon the saving power of His Gospel, and are therefore at rest in all the tumult of mind and public agitation which beset their way."