They will refuse to stop worshiping demons and idols, and they will not repent of their murders, acts of sorcery, immorality, and thievery

As the torment of the demonic hordes begins (9:13-19), the lost will have opportunity to fall on their knees and to beg God for relief and salvation.  But even with a third of mankind slain before their eyes (v. 15), they will harden their hearts, refusing to repent of their sins.  They will refuse to stop worshiping demons and idols (v. 20), and they will not repent of their murders, acts of sorcery, immorality, and thievery (v. 21).  (All references from Revelation)