This rhetorical question is asked to add emphasis. It can be translated as a statement. Alternate translation: "They act as if they do not know anything ... who do not call on Yahweh. But they know what they are doing!" (See: [[rc://en/ta/man/translate/figs-rquestion]])
The abstract nouns "iniquity" can be stated as "evil deeds." Alternate translation: "those who do evil deeds" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])