Mormon spells out the Zoramite apostasy with an unusual level of detail, suggesting that Alma’s original record had even fuller details, which Mormon is abbreviating. In doing so, he also reveals his own expectations. Mormon notes that “they had fallen into great errors” (v. 9), the first of which was rejecting the Mosaic law. It is probable that the Zoramites saw themselves obeying the Mosaic law under their own interpretation. From a Nephite perspective, however, it would seem like a rejection.
Mormon then lists other Zoramite transgressions (vv. 10–11), suggesting that these elements of the Nephite religion are separate from the Mosaic law. He specifically mentions daily prayer. Prayer was certainly part of the Mosaic law.
Mormon is writing his text long after Christ’s visit that subsumed the Mosaic law. Mormon, as a Christian, had also “abandoned” the Mosaic law because Christ had fulfilled it. Thus, the Zoramite had not only abandoned the Mosaic law but also other religious observances that survived Christ’s visit. They were in complete apostasy.