Imputing evil motives to Church leaders as Korihor did (see Alma 30:23–28) was also used by the wicked Nephites in discounting the prophecies of Samuel the Lamanite (see Helaman 16:21). Korihor then denounced the Fall, the Atonement, and revelation—some of the most basic doctrines of the kingdom of God.The word blaspheme, as used in Alma 30:30, means to speak evil of or to revile against God.
Note how Alma explained to Korihor that one of the evidences of the truthfulness of the gospel was the joy it produced in the hearts of the people (see vv. 34–35).