Verses 3-5 consist of the same basic aspect of the coming of the Lord. When the Lord comes in person, he will come as triumphant judge, and those who do not believe at that day will be overcome with guilt. The recognition of the Messiah in those last days will be accompanied by a terrible guilt on behalf of those who “abused his laws.”
Variant: The Printer’s manuscript has “anguishable fire” where the 1830 edition was edited to “unquenchable fire.” (Book of Mormon Critical Text. FARMS 1987 and The Printer’s Manuscript of the Book of Mormon. FARMS, 2001, p. 902.) It is possible that the scribe mis-heard “unquenchable” spoken rapidly and wrote anguishable. It is also possible that it was intended as an emphasis on the misery noted in verse 4. The 1830 text uses “unquenchable” as a more common phrase, modeled after Matthew 3:12 and Luke 3:17.