Aminadab was a Nephite by birth who had belonged to the church of God but dissented from it and lived among the Lamanites. Around 30 B.C., when the missionaries Nephi and Lehi were imprisoned in the land of Nephi and an army came to kill them, the two brothers were encircled by fire that did not burn them, the earth shook, and a cloud of darkness overshadowed those in the prison (Helaman 5:22-28).
Within the darkness, Aminadab turned and saw through the cloud the faces of Nephi and Lehi shining “even as the faces of angels” as they looked toward heaven, and he called out to the multitude to turn and look (Helaman 5:35-37). When the people asked what it meant, Aminadab told them the men were conversing with the angels of God, and that to remove the darkness they must repent and cry to the voice until they had faith in Christ, as taught to them by Alma, Amulek, and Zeezrom (Helaman 5:38-41).
The people cried to God until the cloud dispersed; they saw themselves encircled by fire, the Holy Spirit entered their hearts, a voice spoke peace, and the heavens opened so that angels came down and ministered to them (Helaman 5:42-48). About three hundred people saw and heard these things (Helaman 5:49); they went out to preach throughout the region, and many Lamanites laid down their weapons and yielded their lands to the Nephites (Helaman 5:50-52).