They are under the power of the devil, who is here called ‘the god of this world,’ and elsewhere ‘the prince of this world,’ because of the great interest he has in this world, the homage that is paid to him by multitudes in this world, and the great sway [power] that…he bears in the world, and in the hearts of his subjects, or rather slaves. And as he is the prince of darkness, and the ruler of the darkness of this world, so he darkens the understanding of men, and increases their prejudices, and supports his interest by keeping them in the dark, blinding their minds with ignorance, and error, and prejudices, that they should not behold the ‘light of the glorious gospel of Christ’ (Matthew Henry’s Commentary on the Whole Bible, note on II Corinthians 4:4).