The Nehors' Main Belief
Since the Nehors believed that all mankind would be saved, they "did not believe in the repentance of their sins." (see Alma 1:4 and 15:15)
Amulek "[forsake] all his gold, and silver, and his precious things, which were in the land of Ammonihah, for the word of God, he being rejected by those who were once his friends and also by his father and kindred." "Alma having seen all these things … took Amulek and came over to the land of Zarahemla, and took him to his own house, and did administer unto him in his tribulations, and strengthened him in the Lord." (Alma 15:16, 18)
The Lamanite army that destroyed Ammonihah was the same one that that killed so many of the converts of Ammon and his brethren. This army of Lamanites, after killing the Anti-Nephi-Lehis, became angry because they killed their own brethren, so in response to this anger, they directed their rage at the Nephites. Consequently, they completely wiped out all the people of Ammonihah. (Alma 25:2)
Amulek and Alma were delivered out of prison and Ammonihah on 12th day of the 10th month in the 10th year of the reign of judges (12-10-10). The people of Ammonihah were destroyed by the Lamanites on the 5th day of the 2nd month in the 11th year (5-2-11). So approximately 4 months after the people were warned, they were destroyed.
Christ Would Visit the New World
"They were taught that he would appear unto them after his resurrection." (Alma 16:20)