The rest of mankind, who were not killed by these plagues, did not repent of the works of their hands, so as not to worship demons, and the idols of gold and of silver and of brass and of stone and of wood, which can neither see nor hear nor walk; and they did not repent of their murders nor of their sorceries nor of their immorality nor of their thefts. (Revelation 9:20, 21 NASB)
Men were scorched with fierce heat; and they blasphemed the name of God who has the power over these plagues, and they did not repent so as to give Him glory. Then the fifth angel poured out his bowl on the throne of the beast, and his kingdom became darkened; and they gnawed their tongues because of pain, (Revelation 16:9, 10 NASB)

Our congregation has been reading through Revelation every week for a few months now. Many things have impacted me, but today I want to share the startling lesson from the verses above.
May it never, ever be that my heart would be so cold and hard as to not respond to the discipline of God with humble repentance and reverence for Him. It is simply and utterly chilling to think about what the wicked did as a result of God's just and right punishment. Doesn't it make you shiver with fear for them? What a stark warning:
"and you have forgotten the exhortation which is addressed to you as sons,
"MY SON, DO NOT REGARD LIGHTLY THE DISCIPLINE OF THE LORD,
NOR FAINT WHEN YOU ARE REPROVED BY HIM; FOR THOSE WHOM THE LORD LOVES HE DISCIPLINES,
AND HE SCOURGES EVERY SON WHOM HE RECEIVES." It is for discipline that you endure; God deals with you as with sons; for what son is there whom his father does not discipline?" (Hebrews 12:5-7 NASB)