There is a dilemma here, so let me explain. During the time period leading up to Mormon's life, we find that the Nephites became progressively more wicked. In fact, by the year A.D. 245, we find that "the more wicked part of the people did wax strong, and became exceedingly more numerous than were the people of God" (4 Nephi 1:40). By the year 301, "there were NONE that were righteous save it were the disciples of Jesus" (4 Nephi 1:45, emphasis added). (The reader should note here that the term "disciples" is only used in the Book of Mormon to specifically designate the twelve special witnesses of the Lord, and even more specifically the three who chose not to taste of death.) Moreover, during Mormon's lifetime, there are only two mentions of Mormon even trying to preach to the people:
(1) The first time was when he was fifteen (about A.D. 326) when he was "visited of the Lord, and tasted and knew of the goodness of Jesus" (Mormon 1:15). Mormon notes that he endeavored to preach, but "my mouth was shut, and I was forbidden that I should preach unto them: for behold they had willfully rebelled against their God; and the beloved disciples were taken away out of the land, because of their iniquity" (Mormon 1:16). In this spiritual void Mormon records that "there were no gifts from the Lord, and the Holy Ghost did not come upon ANY, because of their wickedness and unbelief" (Mormon 1:14, emphasis added).
(2) The second time occurred between the years A.D 350 and 360. Mormon notes:
the Lord did say unto me: Cry unto this people--Repent ye, and come unto me, and be ye baptized, and build up again my church, and ye shall be spared. And I did cry unto this people, but it was in vain, and they did not realize that it was the Lord that had spared them, and granted unto them a chance for repentance. And behold, they did harden their hearts against the Lord their God. (Mormon 3:2)
Thus all the textual clues, if interpreted in an "absolute" manner, would seem to eliminate the possibility of an existing Church of Christ during Mormon's lifetime. Yet Mormon spoke his sermon as recorded in Moroni 7 not on repentance, but on faith, hope and charity "as he taught [the people] in the synagogue which they had built for the place of worship. Moreover, Mormon addressed them as his "beloved brethren" (Moroni 7:2), 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" (Moroni 7:3). Furthermore, Mormon told these brethren that he was able to make this judgment "because of your peaceable walk with the children of men" (Moroni 7:4)--strange words from a military leader to an unrighteous and unrepentant mass of degenerate humanity absorbed in the horrors of war. Complicating this scenario are some additional comments found in an epistle of Mormon to Moroni (Moroni 8). It seems Mormon had to write Moroni concerning his son's "ministry" and the "disputations among [the people he was ministering to] concerning the baptism of your little children" (Moroni 8:1-5)--hardly a concern if there was no true Church or there were no righteous people to minister to or baptize into that Church. Thus the Book of Mormon reader is left to formulate a scenario that might give a plausible answer to the dilemma.
For a plausible answer to this dilemma, the reader is referred to Appendix A ("The Chronological Setting for Moroni 7"). [Alan C. Miner, Personal Notes]
Geographical [Theory Map]: Mormon 3:5-8 Lamanites Beaten Twice at Desolation 361 A.S.--362 A.S.