The assembled people whom king Benjamin addressed were those who remained after both a war, and a civil conflict that appears to have escalated to a war. In Words of Mormon (1:16) we are informed that there had been “much contention and many dissensions away unto the Lamanites.” This suggests that those who remained were statistically unified in their support of both Benjamin and of the Nephite religion. It is important to remember that in the ancient world there was no real difference between religion and political systems. God’s laws were the laws of the land and the king represented God’s authority.
When Benjamin says that “I would that ye should do as ye have hitherto done,” he is speaking to those who had previously supported the Nephite religion and political system. Those who could not do so, or at least most who could not do so, had dissented away to the Lamanites. Therefore, it was true that they had been faithful to the commandments.
King Benjamin reiterates the Nephite foundational promise that they would prosper if they kept the commandments. Clearly, there had been times during which they prospered, and Benjamin is promising that blessing for the future. This, in spite of the obvious devastation of war and contention that had recently ended. That clearly non-peaceful event was the result of the unfaithfulness of those who left. Benjamin is contrasting those who remain with those who rejected the Nephite religion and political system and dissented away to the Lamanites. The faithfulness of those present is subtly given credit for the fact that they have survived and that they still have a city and a people.