Nephi went forth “with power,” which, not surprisingly, brought him into conflict with the rulers of the various tribes “because he had greater power than they.” Because of the combination of politics and religion, the tribal rulers were also its religious leaders. (See commentary accompanying Jacob 6:9.) Nephi undermined their authority because he clearly had more religious power than they.
Mormon suggests that the rulers were angry because they could not “disbelieve his words.” In other words, Nephi was preaching powerfully and effectively. Not only are angels ministering to him, but he has power over death (v. 19). Nevertheless, Mormon’s comment has the feel of a religious justification rather than a historical or sociological reason for the fear. It is likely that those who were empowered in their own groups saw Nephi as a threat to restructure the power relationships inside the kin by creating a religious focus that looked outside the local structures.