This question is used to show the shock that the writer feels because the people are so sinful. It can be written as two statements. "Those who commit iniquity act as though they do not know anything. They devour my people as if they were eating bread, and they do not call on God!" (See: [[rc://en/ta/man/translate/figs-rquestion]])
Destroying people is spoken of as devouring them. Doing it as if they were eating bread implies that they did it very easily or without feeling guilty about it. Alternate translation: "those who destroy my people as freely as if they were eating bread" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-simile]])