The Book of Mormon

by Joseph Smith Jr.

I should not show them to any person; neither the breastplate with the Urim and Thummim; only to those to whom I should be commanded to show them; if I did I should be destroyed.

Reminds me of LRH's claim that reading 'Exalibur' or being exposed to OT III materials before you were 'ready' would result in death.

and that these grievous judgments would come on the earth in this generation.

Well, clearly it didn't

by a secular history of the peoples concerned

Non-secular by definition, my dude