Alma (or Mormon) does not include details about Corianton’s misbehavior, but as a missionary, he failed to “give so much heed” to Alma’s words as did his brother but began “boasting in thy strength and… wisdom.” Alma had instructed Shiblon, drawing on the same missionary experience, to be
diligent and temperate in all things.
See that ye are not lifted up unto pride; yea, see that ye do not boast in your own wisdom, nor of your much strength.
Use boldness, but not overbearance; and also see that ye bridle all your passions, that ye may be filled with love; see that ye refrain from idleness.
Do not pray as the Zoramites do, for ye have seen that they pray to be heard of men, and to be praised for their wisdom. (Alma 38:10–13)
The unmistakable parallels between the admonitions to the two brothers about “not boast[ing]” are so conspicuous that there must be a connection. During the Zoramite mission in the same circumstances—and probably during the same episode—Shiblon did not boast of himself, but Corianton did. What might have happened? It is not difficult to imagine a teaching setting where a missionary entered the conceptual fray, confident of his ability to defeat a religious opponent in a doctrinal battle. When the debate showed Corianton’s lack of preparation, knowledge, or debating skills, it also showed his lack of humility. Without the Spirit’s support, he was left to his own “strengths” and was bested in the debate. Rather than impressing others with his testimony, he began to waver in his own faith.
Both Shiblon and Corianton had the same parents, the same background, the same training, and went on the same mission. They came home as very different men. Shiblon was willing to be humble before Yahweh, while the other boasted in his own strength and wisdom, thus manifesting not only a lack of humility but also a totally false sense of security.