Rhetorical: Alma elaborates on the what he desires of his congregation. He has just spoken of those who would deny their culpability, and thus were children of Satan. The reason that Alma gives is that they will not have the good that comes from God, but rather the evil from the devil. In verse 41, this is translated directly into their actions. If one follows the good shepherd, then his actions will be good. If one follows the devil, then his actions will be evil.
Alma is very clearly pointing his sermon at the cessation of the "murders" and "all manner of wickedness" of which he has accused some in the congregation.