After attempting to preach in Ammonihah, Alma turns away, “being weighed down with sorrow.” In that state, an angel appears to him telling him that even though he felt as though he failed in Ammonihah, he yet had “great cause to rejoice.” The divine messenger indicates that it was he who had also appeared to Alma while he was on a very different road for a very different purpose. That appearance altered Alma’s life, and now that messenger tells Alma that it has been successful.
Alma is called to return to Ammonihah and declare that unless they repent, they will be destroyed.
Alma’s father, Alma the elder, was converted by a prophet who had attempted to preach, but was rejected by the people of Lehi-Nephi. The Lord told that prophet, Abinadi, to return and preach. It was not specified that Abinadi preach destruction, but he did prophecy the coming death of King Noah, and the bondage of the people.
There is therefore a subtle subtext to the story of Alma the younger in Ammonihah. Abinadi’s similar rejection and divine call to return converted his father. Perhaps that is the message for Alma the younger, that he might not change the prophesied course, but that he would make important converts.