Moroni’s secret abominations are the same as the secret combinations—alternate terms for the same phenomenon. Book of Mormon secret combinations are characterized by murder for gain (Hel. 1:9, 6:15, 8:27). Moroni therefore describes the effects of such murders—causing widows and orphans to mourn. Moroni may also be referencing the murderings and plunderings that characterize Lamanites, Nehors, and Gadiantons. (See commentary accompanying Alma 17:14, 50:21, and Helaman 6:17.)