More especially, they are exposed to the following reply. If visible things are the work of the evil god, what is the work of the good God? For nothing is to be seen except the work of the Artificer. Or what evidence is there that the good God exists at all, if there are no works of His by which He may be known? For by his works the artificer is known. 2. Or how could two principles exist, contrary one to another: or what is it that divides them, for them to exist apart? For it is impossible for them to exist together, because they are mutually destructive. But neither can the one be included in the other, their nature being unmixed and unlike. Accordingly that which divides them will evidently be of a third nature, and itself God. But of what nature could this third something be? good or evil? It will be impossible to determine, for it cannot be of the nature of both. 3. This conceit of theirs, then, being evidently rotten, the truth of the Church's theology must be manifest: that evil has not from the beginning been with God or in God, nor has any substantive existence; but that men, in default of the vision of good, began to devise and imagine for themselves what was not, after their own pleasure. 4. For as if a man, when the sun is shining, and the whole earth illumined by his light, were to shut fast his eyes and imagine darkness where no darkness exists, and then walk wandering as if in darkness, often falling and going down steep places, thinking it was dark and not light—for, imagining that he sees, he does not see at all—so, too, the soul of man, shutting fast her eyes, by which she is able to see God, has imagined evil for herself, and moving therein, knows not that, thinking she is doing something, she is doing nothing. For she is imagining what is not, nor is she abiding in her original nature; but what she is is evidently the product of her own disorder. 5. For she is made to see God, and to be enlightened by Him; but of her own accord in God's stead she has sought corruptible things and darkness, as the Spirit says somewhere in writing, “God made man upright, but they have sought out many inventions.” Thus it has been then that men from the first discovered and contrived and imagined evil for themselves. But it is now time to say how they came down to the madness of idolatry, that you may know that the invention of idols is wholly due, not to good but to evil. But what has its origin in evil can never be pronounced good in any point—being evil altogether.
8. The origin of idolatry is similar. The soul, materialised by forgetting God, and engrossed in earthly things, makes them into gods. The race of men descends into a hopeless depth of delusion and superstition.
Now the soul of mankind, not satisfied with the devising of evil, began by degrees to venture upon what is worse still. For having experience of diversities of pleasures, and girt about with oblivion of things divine; being pleased moreover and having in view the passions of the body, and nothing but things present and opinions about them, ceased to think that anything existed beyond what is seen, or that anything was good save things temporal and bodily; so turning away and forgetting that she was in the image of the good God, she no longer, by the power which is in her, sees God the Word after whose likeness she is made; but having departed from herself, imagines and feigns what is not. 2. For hiding, by the complications of bodily lusts, the mirror which, as it were, is in her, by which alone she had the power of seeing the Image of the Father, she no longer sees what a soul ought to behold, but is carried about by everything, and only sees the things which come under the senses. Hence, weighted with all fleshly desire, and distracted among the impressions of these things, she imagines that the God Whom her understanding has forgotten is to be found in bodily and sensible things, giving to things seen the name of God, and glorifying only those things which she desires and which are pleasant to her eyes. 3. Accordingly, evil is the cause which brings idolatry in its train; for men, having learned to contrive evil, which is no reality in itself, in like manner feigned for themselves as gods beings that had no real existence. Just, then, as though a man had plunged into the deep, and no longer saw the light, nor what appears by light, because his eyes are turned downwards, and the water is all above him; and, perceiving only the things in the deep, thinks that nothing exists beside them, but that the things he sees are the only true realities; so the men of former time, having lost their reason, and plunged into the lusts and imaginations of carnal things, and forgotten the knowledge and glory of God, their reasoning being dull, or rather following unreason, made gods for themselves of things seen, glorifying the creature rather than the Creator, and deifying the works rather than the Master, God, their Cause and Artificer. 4. But just as, according to the above simile, men who plunge into the deep, the deeper they go down, advance into darker and deeper places, so it is with mankind. For they did not keep to idolatry in a simple form, nor did they abide in that with which they began; but the longer they went on in their first condition, the more new superstitions they invented: and, not satiated with the first evils, they again filled themselves. with others, advancing further in utter shamefulness, and surpassing themselves in impiety. But to this the divine Scripture testifies when it says, “When the wicked comes unto the depth of evils, he despises.”
9. The various developments of idolatry: worship of the heavenly bodies, the elements, natural objects, fabulous creatures, personified lusts, men living and dead. The case of Antinous, and of the deified Emperors.
Source: Against the Heathen (New Advent)