A people (the Nephites) will speak as a voice from the dust—The Apostasy, restoration of the gospel, and coming forth of a sealed book (the Book of Mormon) are foretold—Compare 2 Nephi 27.
Part of the kingdom of the devil being shaken up includes revealing the acts of wickedness to the world.
I think it shows the absolute confidence of the people, that they boldly proclaim that their works are unknown. Also, it shows that they are aware of their wicked deeds – they do not sin ignorantly. In the last days, the works of their own hands will testify against them (Isaiah 19:16). They will witness not only the creator that made them, but that they were aware of what they were doing.
To take the Lord's name in vain means to use it without authority. Irreverence is another way.
The Book of Mormon exposes the enemies of Christ (Pres Benson), Ensign, January 1988.
"Every man eventually is backed up to the wall of faith, and there he must take his stand." A Witness and a Warning (Pres Benson)
What a great promise in verse 20.
Isaiah 29:21 - these are those that shall be cut off, and in the days of the Book of Mormon, these are the designs of the wicked:
Isaiah 29:22 - the Lord claims the credit, He is the one who "redeemed Abraham." Jacob won't be worried ("neither shall his face now wax pale").