The people had said that they did not believe Alma’s prophecy that they would be destroyed (see verse 4). Alma’s response has been to show that only Jehovah’s protection has prevented the Nephite destruction on many occasions. Now he reiterates that concept, but directs the blame directly upon the people of Ammonihah. It is no longer about the Nephites in general, but this city in particular. The promise is that they will be destroyed unless they repent.
Jehovah, in His mercy, is giving them another opportunity to repent. It is that opportunity that Alma offers them. It is important to note that a significant aspect of their repentance is to realize that “not many days hence the Son of God shall come in his glory.” One of the common traits of Nephite apostasy was the rejection of the doctrine of the coming Messiah. Therefore, Alma mentions it as an important part of repenting. Of course, Alma understands that repentance comes only through the atoning mission of the Messiah.
The final solution is to repent and be baptized into the church that the people of Ammonihah have rejected.