7. And, what is more miserable, even they, already made as it were our own, cannot find how they may believe us. For if they suspect that even in the catholic doctrines themselves we speak lyingly, that we may conceal I know not what other thing which we think true; of course to one suspecting the like thou shalt say, I did this then only to catch thee: but what wilt thou answer when he says, Whence then do I know whether thou art not doing it even now, lest thou be caught by me? Or indeed, can any man be made to believe that a man does not lie not to be caught, who lies to catch? Seest thou whither this evil tends? that is, that not only we to them, and they to us, but every brother to every brother shall not undeservedly become suspected? And so while that which is aimed at by means of the lie, is that faith may be taught, the thing which is brought about is, rather, that there shall be no having faith in any man. For if we speak even against God when we tell a lie, what so great evil will people be able to discover in any lie, that, as though it were a most wretched thing, we should be bound in every way to eschew it?
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 1, vol. 3 (Schaff, 1887), public domain (Public domain).