“41 And Aminadab said unto them: You must repent, and cry unto the voice, even until ye shall have faith in Christ, who was taught unto you by Alma, and Amulek, and Zeezrom”
It’s worth noting that here we have Nephi and Lehi preaching to the Lamanites in the land of Nephi. Yet, they find a former Nephite living among the Lamanites. And this Nephite reminds the Lamanites of sermons that were preached by Alma, Amulek, and Zeezrom to Nephites living in Nephite lands.
This story illustrates that the neat divide between Nephite and Lamanite that Mormon identifies was likely not nearly as neat and tidy as he suggests. At this time, We see former Nephites going over to the Lamanites and living among the Lamanites without obvious stigma. We see Nephite sermons being widely known not just among the Nephites, but also parts of the Lamanites. Such a society allowed for a flourishing of missionary work among the Lamanites, but it perhaps perversely also allowed false ideas from the Lamanites to infiltrate Nephite society.