18 But some one on the opposite side says, How do we know whether the theologians have written what is certain and well known, or set forth a wanton fiction, as they thought and judged? That has nothing to do with the matter; nor does the reasonableness of your argument depend upon this—whether the facts are as the writings of the theologians state, or are otherwise and markedly different. For to us it is enough to speak of things which come before the public; and we need not inquire what is true, but only confute and disprove that which lies open to all, and which men's thoughts have generally received.
But if they are liars, declare yourselves what is the truth, and disclose the unassailable mystery. And how can it be done when the services of men of letters are set aside? For what is there which can be said about. the immortal gods that has not reached men's thoughts from what has been written by men on these subjects? Or can you relate anything yourselves about their rights and ceremonies, which has not been recorded in books, and made known by what authors have written? Or if you think these of no importance, let all the books be destroyed which have been composed about the gods for you by theologians, pontiffs, and even some devoted to the study of philosophy; nay, let us rather suppose that from the foundation of the world no man ever wrote anything about the gods: we wish to find out, and desire to know, whether you can mutter or murmur in mentioning the gods, or conceive those in thought to whom no idea from any book gave shape in your minds.
But when it is clear that you have been informed of their names and powers by the suggestions of books, it is unjust to deny the reliableness of these books by whose testimony and authority you establish what you say.
Source: Against the Heathen (New Advent)