34 But why do I complain that you have disregarded the insults offered to the other deities? That very Jupiter, whose name you should not have spoken without fear and trembling over your whole body, is described as confessing his faults when overcome by lust of his wife, and, hardened in shamelessness, making known, as if he were mad and ignorant, the mistresses he preferred to his spouse, the concubines he preferred to his wife; you say that those who have uttered so marvellous things are chiefs and kings among poets endowed with godlike genius, that they are persons most holy; and so utterly have you lost sight of your duty in the matters of religion which you bring forward, that words are of more importance, in your opinion, than the profaned majesty of the immortals.
So then, if only you felt any fear of the gods, or believed with confident and unhesitating assurance that they existed at all, should you not, by bills, by popular votes, by fear of the senate's decrees, have hindered, prevented, and forbidden any one to speak at random of the gods otherwise than in a pious manner? Nor have they obtained this honour even at your hands, that you should repel insults offered to them by the same laws by which you ward them off from yourselves.
They are accused of treason among you who have whispered any evil about your kings. To degrade a magistrate, or use insulting language to a senator, you have made by decree a crime, followed by the severest punishment. To write a satirical poem, by which a slur is cast upon the reputation and character of another, you determined, by the decrees of the decemvirs, should not go unpunished; and that no one might assail your ears with too wanton abuse, you established formulae for severe affronts.
With you only the gods are unhonoured, contemptible, vile; against whom you allow any one liberty to say what he will, to accuse them of the deeds of baseness which his lust has invented and devised. And yet you do not blush to raise against us the charge of want of regard for deities so infamous, although it is much better to disbelieve the existence of the gods than to think they are such, and of such repute.
Source: Against the Heathen (New Advent)