In Mormon 2:15, Mormon had indicated that: “I saw that the day of grace was passed with them, both temporally and spiritually.” In spite of this “day of grace” having passed them, they were not yet at the point where the Lord was unwilling to attempt to supply that grace to them. Mormon engaged the people in the task that had the only temporal chance of their salvation, the building of defenses. The Lord charges Mormon to also provide them with the only defense against their spiritual destruction, which was to preach the gospel to them. Because of the Nephite’s foundational promise that they would be preserved in the land, this was also a promise of divine assistance in the temporal protection as well. The Lord directed Mormon to do for his people the very thing that would save them.
The Lord ever works in this way. He tells us what we need. Sadly, we frequently do not see what we need as what we want. The Nephites had that very problem, and serve as poignant reminders of the ultimate consequences of electing our present wants over our eternal needs.