The devil, Satan.Then please explain who the "god of this age" of 2 Cor 4:4 is.
He is called that and elsewhere in the Bible he is called the "prince of this world" because of the great interest he has in this world, as well as the homage that is paid to him by many people in this world, and the great influence that he exercises in the world, and in the hearts and minds of his subjects, or rather slaves.
Just note "god" -- little g, not the God.