9:1–12 The trumpet blast sets in motion a horrific army of locusts, energized by demonic sources (vv. 1, 2). The imagery derives from Ex. 10:13–15 and Joel 2:1–11, where a literal locust plague foreshadows even more devastating judgment coming from a divinely commissioned army (Joel 2:11). Their terrorizing powers compare only to those of the beast (13:1–10). These infernal monsters attack only the wicked, not the saints (v. 4).
The wicked sometimes suffer even in this life as a preview of their final punishment (20:11–15). According to idealist interpreters (Introduction: Interpretive Difficulties), the vision depicts the self-defeating and tormenting nature of wickedness in the human soul. Powers from the abyss attack not the saints but only the wicked. Historicists have generally seen the vision as a depiction of Islamic conquest of a degenerate Western Europe (a.d. 612–762), but such an application would be only one embodiment of the principle, and an imperfect one at that. Futurists understand the vision as a supernatural plague of demonic spirits, to be loosed on the earth shortly before the Second Coming. The fundamental principle is the same in all these interpretations, and multiple applications of the principle are possible.