Rhetorical: Alma emphasizes the seriousness of their sin by contrasting their state with that of Abraham, Isaac, and Jacob. Why should Alma assume that this argument will impress his people? Does he really expect that they believe that they compare with those prophets? The answer is not in the comparison, but in the "place to sit down" with. One of the aspects of heaven that became a metaphor for the future life was that one might be in the bosom of the prophets (see Luke 16:23). Clearly Alma's congregation held to a similar notion that heaven would be where they would have place with the prophets. What Alma is telling them is that heaven is denied them unless they repent.