Even without the details of the wars or the people involved, Mormon does have a reason for telling his readers about this war, and he makes sure that they understand it in verses 11–13. It “would not have happened had it not been for their wickedness and their abomination which was among them; yea, and it was among those also who professed to belong to the church of God.”
The promise of the land is that the people will prosper on the land if they are righteous. Alma gave his son, Shiblon, the clear example of the two parts of the promise: “Inasmuch as ye shall keep the commandments of God ye shall prosper in the land; and inasmuch as ye will not keep the commandments of God ye shall be cut off from his presence” (Alma 38:1).
The cause of the destruction might be war, but the cause of the dissensions, and therefore the war, was “because of the pride of their hearts, because of their exceeding riches, ye, it was because of their oppression to the poor, withholding their food from the hungry, withholding their clothing from the naked, and smiting their humble brethren.” This is the antithesis of Nephite religion. It is also the hallmark of Nephite society when they succumb to the temptations of attempting to be too much like their powerful surrounding cultures.