Because many Nephites undoubtedly stayed in the land of Zarahemla, the two brothers were preaching to people who had previously lived under Nephite rule and religion. (See commentary accompanying Helaman 4:17–19.) This mission was not necessarily to the “heathen” but to dissenters.
This verse could indicate two types of dissenters. The first are the political dissenters who have created havoc in Nephite government for the past fifty years out of a strong personal preference for the Lamanite system. They had gone through the process of rejecting Nephite traditional beliefs, desiring to adopt a new lifestyle, justifying that separation, and engaging in acts of political rebellion, even armed warfare, or physically moving into Lamanite-held territory.
The second type of dissenter—and the more likely target of Nephi’s preaching—were dissenters of convenience. They were committed to their own ancestral farms and fields, who decided not to leave during the exodus to Bountiful. Traditionally, these people had seen governments (and religions) come and go; they remained faithful to their fields and the cycle of the seasons.