8 we have therefore— as I suppose— shown sufficiently, that to the immortal gods temples have been either reared in vain, or built in consequence of insulting opinions held to their dishonour and to the belittling of the power believed to be in their hands. We have next to say something about statues and images, which you form with much skill, and tend with religious care—wherein if there is any credibility, we can by no amount of consideration settle in our own minds whether you do this in earnest and with a serious purpose, or amuse yourselves in childish dreams by mocking at these very things. For if you are assured that the gods exist whom you suppose, and that they live in the highest regions of heaven, what cause, what reason, is there that those images should be fashioned by you, when you have true beings to whom you may pour forth prayers, and from whom you may, ask help in trying circumstances?
But if, on the contrary, you do not believe, or, to speak with moderation, are in doubt, in this case, also, what reason is there, pray, to fashion and set up images of doubtful beings, and to form with vain imitation what you do not believe to exist? Do you perchance say, that under these images of deities there is displayed to you their presence, as it were, and that, because it has not been given you to see the gods, they are worshipped in this fashion, and the duties owed to them paid? He who says and asserts this, does not believe that the gods exist; and he is proved not to put faith in his own religion, to whom it is necessary to see what he may hold, lest that which being obscure is not seen, may happen to be vain.
Source: Against the Heathen (New Advent)