2 Corinthians 4:4
In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them.
I know we've looked at this from several perspectives. I'd always understood the term "god of this world" to refer to Satan, the "god of this age" or "world system".
We essentially see two kingdoms. One is a heavenly kingdom, the other is a kingdom of this world.