The term used here denotes a change of mind. Through the pressure the Lord placed upon humanity by pouring out the bowls of his wrath, God sought change in people’s thinking so that they would take God seriously and glorify him. Glorifying God, after all, was the reason for man’s existence (Isaiah 43:7; Matthew 6:9) and was the reason why God equipped humanity with the gifts initially given in Paradise. But such is the hardness and stubbornness of man’s fallen heart that he refuses to repent, even in the face of a calamity that he can do nothing about (technologically speaking). This refusal is repeated in Revelation 16:11.
9 They were scorched by the fierce heat, and they cursed the name of God who had power over these plagues. They did not repent and give him glory.