Alma rebukes Corianton for a second fault. In addition to boasting, Corianton “didst do that which was grievous unto me.” There are two parts to what Alma considered “most grievous.” First, Corianton “did forsake the ministry” and secondly “did go over” to Lamanite territory “after the harlot Isabel.” The first grievous transgression Alma lists is forsaking the ministry. The entire context of Alma’s blessing/exhortation to Corianton focuses on doctrinal issues rather than the incident with Isabel. More than just forsaking the ministry, something occurred during this mission that caused Corianton to also begin to forsake Nephite religion.
Alma does not mention doctrinal errors that Corianton started to believe but rather his “go[ing] after” the harlot Isabel. It is significant that Isabel was located “among the borders of the Lamanites.” She was apparently a Lamanite. To reach her, Corianton had to physically move toward the Lamanites, but he also moved culturally in that direction. He abandoned his mission, not to return to Zarahemla, his home, but to head in the opposite direction both physically and spiritually.
Considering the fact that only six women in the Book of Mormon are named (and three of them, Eve, Sarah, and Mary, are biblical women), it is remarkable that Isabel’s name is recorded. This fact alone suggests her importance but doesn’t give us enough of a hint to know why she was sufficiently important to name.