10 On the other hand, let us be far from supposing that the devil is called in any such way the prince of the world, as that we should believe him possessed of power to rule over the heaven and the earth. The world is so spoken of in respect of wicked men, who have overspread the whole earth; just as a house is spoken of in respect to its inhabitants, and we accordingly say, It is a good house, or a bad house; not as finding fault with, or approving of, the erection of walls and roofs, but the morals either of the good or the bad within it. In a similar way, therefore, it is said, “The prince of this world;” that is, the prince of all the wicked who inhabit this world. The world is also spoken of in respect to the good, who in like manner have overspread the whole earth; and hence the apostle says, “God was in Christ, reconciling the world unto Himself.” These are they out of whose hearts the prince of this world is ejected.
Source: Tractates on the Gospel of John (New Advent)