As Mormon begins to preach, he declares the authority by which he speaks. This is not a declaration of priesthood authority, but rather of spiritual authority, the Spirit being a part of the community of those who have taken upon themselves the name of Christ. As an example of how our sermons might be, Mormon would suggest that we express our ideas as the Spirit motivates us.
There is a difference between Mormon’s authority and the authority that most of us bring to our talks. He is a leader in the church, and is therefore able to address “you that are of the church,” and to be able to make statements that go far beyond most statements that we make in Sacrament meetings. Mormon, therefore, can declare that “[you] have obtained a sufficient hope by which ye can enter into the rest of the Lord.” Although we can learn something from him as a speaker, we also remember that he is an Apostle, and therefore able to make such pronouncements.