Amalickiah had his supporters, and his supporters were among the lower judges (see verse 4). That meant that they had recognized positions of authority that were leading the people astray. Moroni needed to rally the people to the cause of the Nephite religion, or the cause of liberty. Therefore, he uses the banner to make himself more visible in crowds. In addition to those who could read the writing on the banner, he vocally proclaimed the message. It was a call to arms from the people of the land. There was no standing army, and Moroni had to compete with Amalickiah for army recruits.