Alma discovers his son, Corianton, has been getting sexual favors from Isabel, in the land of Siron. He begins to rebuke Corianton for this act (Book of Mormon, Alma 39:4-5), but then gives a dissertation to him about how his act is third only in severity to murder, and the denial of the Holy Ghost.
If Alma simply mentioned this in passing it would be one thing, but while he was in the middle of chastising Corianton for his immorality, he spends the next 69 words (in verse 6) explaining how a crime of which Corianton was NOT guilty of, was even worse than his rendezvous with Isabel.
This deviation in conversation seems unlikely, and serves to leave one scratching their head as to why this diversion takes place at all, when the space for writing in the plates is so limited. The segue from verse 6 into verse 7 is so clumsy, the reader almost forgets the reason Alma is angry at his son.
You’re left thinking he was guilty of the greater sins.