Cary answered...

Faith is a huge topic, rarely fully understood even by people who talk about it a lot. In the Mormon conception, it's a step of confidence between mere belief and full knowledge. It's perhaps best described by contrast with these two extremes on the continuum on which they all lie. First, faith is not that passive thing we call belief because it's a principle of action. So for someone to have faith, they have to be motivated to put a belief into practice, not merely be content with keeping it in their mind. For example, we believe that Christ is the Savior, but because we have faith we ACT as if this were true, and follow His example as best we can. In fact, "acting as if..." is a fairly good phrase to define faith. On the other hand, faith is not "perfect knowledge" either. There is enough of an element of uncertainty about the thing we have faith in, that it takes an effort of conscious decision-making to test our faith's hypothesis. If we had a full knowledge of a thing, that whole test, and the faith to find out if it's true, wouldn't be necessary. Atheists will argue that faith is mere belief (and baseless, at that), but what I have described for faith here leads to a more "scientific" approach that Atheists would like to admit is operable in the minds of the faithful. The proper response to a scriptural assertion, then, becomes not blind obedience, but rather careful thought, hypothesis forming, and testing. As tests come back proven or unproven, faith will grow in the right direction until it approaches "perfect knowledge".