Instead of using “faith” as you do in your introduction, I propose “trust.”

Faith seems more of a binary state — either you believe or you do not believe. Worse, “faith” has become a loaded word lately, especially here in the US. It now often connotes a blind acceptance, with the implication that there is no evidence to form a basis for a given belief. Godless heathens like me dismiss most religious beliefs for this reason. The more extreme on the other side try to turn the term around, characterizing my belief in, say, evolution, as also (just) a matter of faith, implying that it is equally baseless.

Trust, on the other hand, seems more of a continuum. It connotes a sliding scale. We often use phrases like “he’s pretty trustworthy” and “I can trust her on this.” Further, the degree of trust in a given source is continually readjusted, based on observed results obtained from relying on this source. Referring to your comparison of the skeptical and the naive, I might stretch my analogy of a sliding scale to say that the latter have less fine granularity available to them. Think of the volume knob on a radio with a limited set of fixed positions. The ultimate in naivete comes when there are only two positions available on the dial.

It seems to me that another distinction can be drawn by examining your behavior when options are available. If you trust something, you’ll still likely double-check it, or plan a fallback position, if these options aren’t too expensive. If you have faith in something, however, you don’t bother. This seems to equate faith with 100% trust.

(Please pardon my Americanisms: I could not make myself type “sceptical.”)