In C.S. Lewis' The Lion, the Witch, and the Wardrobe, when Peter and Susan go to speak with the Professor (who is Digory Kirke, the magician's nephew) about their younger sister Lucy's insistence that she has visited Narnia by passing through a wardrobe located in a spare room in the Professor's house and their younger brother (who is older than Lucy) Edmund's denial that he visited Narnia, despite the fact that he did (a fact not known to Susan and Peter at this point in the story) and Edmund's hostility towards Lucy, the Professor proves wise.
After listening for a long time without speaking, the Professor says, "if you will excuse me for asking the question - does your experience lead you to regard your brother [Edmund] or your sister [Lucy] as the more reliable? I mean, which is the more truthful?" Peter replies, "Up till now I'd have said it was Lucy every time." When asked by the Professor, Susan concurs with Peter's assessment, adding, "but this couldn't be true about the wood and the faun."
The Professor continues by telling the concerned elder siblings that "a charge of lying against someone whom you have always found truthful is a very serious thing: a very serious thing indeed." Susan quickly replies, "We were afraid it mightn't be lying,... we thought there might be something wrong with Lucy." The Professor asks "coolly," "Madness, you mean?" He observes that all one has to do to learn that Lucy is not "mad" is to speak with her.
"Logic!" says the Professor. "Why don't they teach logic at these schools? There are are only three possibilities. Either your sister is telling lies, or she is mad, or she is telling the truth. You know she doesn't tell lies and it is obvious that she is not mad. For the moment then and unless any further evidence turns up, we must assume that she is telling the truth."
In addition to being very consonant with how Don Gius explains faith using a quite ordinary, if somewhat complex, example, what Lewis puts into the mouth of Professor Digory Kirke is also very congruent with philosopher Alvin Plantinga's epistemological concept of "warrant," laid out initially in his book Warrant and Proper Function, which was newly published and all the rage back when I was a university philosophy student. In modern analytic philosophy knowledge is usually held to be the result of a justified, true, belief. But since "true" is too objective, that is, external to the subject, and "belief" is too subjective, that is, internal to the subject, much emphasis is placed on justifying what we can believe.
While this is most certainly an oversimplification and assuming memory serves me well, Plantinga proposed "warrant" as something like a replacement for "justified" in this schema. Warrant holds something along the lines that assuming the human subject is functioning properly (i.e., not "mad" and is being honest) and no evidence can "undercut" (i.e., refute) the belief, then it doesn't need to be justified, the subject has warrant (i.e., is epistemically "authorized") to believe it.
Lewis used a similar argument in Mere Christianity:
I am trying here to prevent anyone saying the really foolish thing that people often say about [Jesus]: “I’m ready to accept Jesus as a great moral teacher, but I don’t accept His claim to be God.” That is the one thing we must not say. A man who said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic — on a level with the man who says he is a poached egg — or else he would be the Devil of Hell. You must make your choice. Either this man was, and is, the Son of God: or else a madman or something worse. You can shut Him up for a fool, you can spit at Him and kill Him as a demon; or you can fall at His feet and call Him Lord and God. But let us not come with any patronizing nonsense about His being a great human teacher. He has not left that open to us. He did not intend to.It seems to me that if there's one thing that overeager atheists most often lack, it is anything remotely resembling an epistemology. In every instance, as J.R.R. Tolkien told the younger, not yet believing C.S. Lewis, they lack imagination, choosing a two-dimensional view.