I recently read An Agnostic's Apology, by Leslie Stephen, which presents a splendid analysis of why a reasonable person should be agnostic. To be agnostic is also to be atheist, of course, so I tend to use the terms interchangeably.
Towards the end he says:
Why, when no honest man will deny in private that every ultimate problem is wrapped in the profoundest mystery, do honest men proclaim in pulpits that unhesitating certainty is the duty of the most foolish and ignorant? Is it not a spectacle to make the angels laugh? We are a company of ignorant beings, feeling our way through mists and darkness, learning only by incessantly repeated blunders, obtaining a glimmering of truth by falling into every conceivable error, dimly discerning light enough for our daily needs, but hopelessly differing whenever we attempt to describe the ultimate origin or end of our paths; and yet, when one of us ventures to declare that we don't know the map of the universe as well as the map of our infinitesimal parish, he is hooted, reviled, and perhaps told that he will be damned to all eternity for his faithlessness.
I've often written along similar lines myself, only a lot less elegantly :-).
I've been trying to analyse the concept of doubt in recent blog posts, and how that relates to faith. Certainly some theists admit to some doubt, although many don't, and *my* interpretation of faith is one of banishing doubt and committing to an unjustified belief. Others claim they have access to some universal 'truth'.
The splendid last paragraph of Stephen's 1893 essay says, in response to the convictionalist challenge to "Stick to the words which profess to explain everything; call your doubts mysteries, and they won't disturb you any longer; and believe in those necessary truths of which no two philosophers have ever succeeded in giving the same version."
Gentlemen, we can only reply, wait till you have some show of agreement amongst yourselves. Wait till you can give some answer not palpably a verbal answer, to some one of the doubts which oppress us as they oppress you. Wait till you can point to some single truth, however trifling, which has been discovered by your method, and will stand the test of discussion and verification. Wait till you can appeal to reason without in the same breath vilifying reason. Wait till your Divine revelations have something more to reveal than the hope that the hideous doubts which they suggest may possibly be without foundation. Till then we shall be content to admit openly, what you whisper under your breath or hide in technical jargon, that the ancient secret is a secret still; that man knows nothing of the Infinite and Absolute; and that, knowing nothing, he had better not be dogmatic about his ignorance. And, meanwhile, we will endeavour to be as charitable as possible, and whilst you trumpet forth officially your contempt for our skepticism, we will at least try to believe that you are imposed upon by your own bluster.
This could have been written today in response to the Stanley Fishes and Terry Eagletons of this world.