Faith needs reason. If we take faith to be mere belief or even a claim to knowledge without any compelling reasons for that claim, as we often do, then it is obviously true that faith and reason are mutually exclusive.
When we talk about faith we often slip into a semi-philosophical or semi-theological way of thinking and talking. When we do, we are likely to make it a matter of belief without reasons. But I think that way of talking about faith is mistaken.
One problem is that those who think about faith that way confuse faith with opinion. If we confuse the two, then we shouldn't be surprised when the arguments showing the insufficiency of opinion and the necessity of moving beyond opinion to knowledge also work as arguments against faith.
But suppose that faith is not a version of opinion, a poorly grounded opinion. If not, we should be skeptical that faith is contrary to reason.
There is scriptural evidence for that skepticism. Paul, for example, is explicit about faith being a matter of evidence: "Now faith is the substance (hypostasis; meaning "reality" or "realization") of things hoped for, the evidence (elenchos, meaning "proof" or "argument for" ) of things not seen" (Heb. 11:1).
And in the Book of Mormon, two missionaries convert hundreds to faith by offering them "great evidence" (see Helaman 5:50). Several years later, a Book of Mormon prophet tells the people that their unbelief is unreasonable, a rejection of convincing evidence (see Helaman 8:24).
Faith has reasons and requires them. But it is essentially trust and fidelity rather than belief. Beliefs will result from trust and fidelity, and when they do, they will have their reasonable ground in that trust and its consequences. So a better understanding of faith, one that has the advantage of conforming to the use of the word in scripture, is "fidelity to something that one has been given, such as an experience or covenant, or fidelity to and trust in someone, such as God."
I find it interesting that such a description is similar to what we might say of knowledge. As David Banon says, for biblical writers the basic structure of knowledge is not possession, but "fidelity" (Lecture infinie 173). To know something or someone (and the latter is the model for the former) isn't to "get it," but to trust.
We don't usually think about knowledge in Hebrew rather than Greek terms, but perhaps we should consider doing so. Talking about faith in terms of fidelity means making the distinction between faith and knowledge less clear. In fact, if we think about knowledge in these terms, we might say that just as faith requires reason, reason turns out to need something like faith, though not always religious faith.
The definition of reason is a project that has turned out to be knotty and one that I don't claim to have undone. I don't pretend to do that here. But, following Banon's remark about the Hebrew understanding of knowledge, it may be helpful to notice that reason is fundamentally a responsible response to a call, a demand, from someone or something. Reason too is a response to something given to us, something that comes to us without our having chosen it.
We often associate reasoning with questioning: we need reason because questions arise, and because we question in order to learn. But as one of my teachers, Otto Pöggeler, pointed out, the essence of rational thought isn't questioning, though of course every thinker must question. The essence of thought isn't questioning because questioning relies on the fact that when I question I already find myself called by something to which I submit myself, something that demands my attention and response.
When I question, something has authority over me, always the physical world, sometimes another person, always God. I cannot question unless I am already in a world that makes demands on me to which I must respond. The appropriateness of my response is its degree of rationality. In being a response to a demand from outside oneself, reason is like the response of religious faith, even when it is a response to something other than God.
As a Mormon, my understanding of the relation of faith and reason is simple: We find ourselves in the world, surrounded by things and people, and standing before God, all of which lay claim on us, call us, making demands that we respond, that we account for ourselves, that we act.
Believers know that we initially found ourselves before God, our Creator. Even if (as Mormons believe) creation was not ex nihilo, he called us into existence and continues to call us: "Hear, oh Israel."