30 But in the discussion which we at present maintain, we do not undertake this trouble or service, to show and declare who all these were. But this is what we proposed to ourselves, that as you call us impious and irreligious, and, on the other hand, maintain that you are pious and serve the gods, we should prove and make manifest that by no men are they treated with less respect than by you. But if it is proved by the very insults that it is so, it must, as a consequence, be understood that it is you who rouse the gods to fierce and terrible rage, because you either listen to or believe, or yourselves invent about them, stories so degrading. For it is not he who is anxiously thinking of religious rites, and slays spotless victims, who gives piles of incense to be burned with fire, not he must be thought to worship the deities, or alone discharge the duties of religion. True worship is in the heart, and a belief worthy of the gods; nor does it at all avail to bring blood and gore, if you believe about them things which are not only far remote from and unlike their nature, but even to some extent stain and disgrace both their dignity and virtue.
Source: Against the Heathen (New Advent)