The rest of mankind, who were not killed by these plagues, did not repent of the works of their hands nor give up worshiping demons and idols of gold and silver and bronze and stone and wood, which cannot see or hear or walk, nor did they repent of their murders or their sorceries or their sexual immorality or their thefts. – Revelation 9:20-21 ESV
The sounding of the fifth and sixth trumpets have unleashed devastation on the earth in the form of demon oppression, and the unleashing of some form of army, either human or demonic, that will kill a third of mankind. Regardless how one views these two woes, they represent a terrible time of judgement on the peoples of earth.
But I have to wonder why? Judgement against unbelievers will last for an eternity, so why this period of time while still on earth? And I think this verse may give an answer to that question. Those not killed by the armies of the sixth trumpet did not repent. Was that the goal of this judgement, to bring people to repent and turn to God? It is possible that this time of judgement is one last opportunity for people to turn to God before it is to late and they enter into the final judgement and eternity.
If so, that makes this passage heartbreaking. Even after getting a taste of God’s judgement, mankind does not repent; either of the work of their hands, their false worship of created things (Rom. 1:21-23), or their other sins. Instead it is likely that they further harden their hearts and look for ways to overcome this judgement by human means. So like today.