When the Spirit justified killing Laban to retrieve the brass plates, he said: “Behold the Lord slayeth the wicked to bring forth his righteous purposes. It is better that one man should perish than that a nation should dwindle and perish in unbelief” (1 Nephi 4:13). Alma tells Helaman that the brass plates have more than fulfilled their promise of preserving the teachings necessary to understand and fulfill their covenant with Jehovah, even more than just teaching the Nephites that the teachings of the brass plates had convinced “so many thousands of the Lamanites.”
The small and simple thing of preserving the brass plates led to the preservation of the covenant among the Nephites, the conversion of many thousands of the Lamanites, and the important teaching that they were “to rejoice in Jesus Christ their Redeemer.” Alma hopes that if those teaching can turn the hearts of many thousands of the Lamanites, they may also do so for those many Nephites who had been hardening their hearts against the Nephite teachings. The most recent and relevant example may have been the Zoramites in Antionum, but Alma had given up the judgment seat to preach in other locations, such as Ammonihah.