--Moroni 7:26 [emphasis added]
There is a common myth within Mormonism of two missionaries stranded in the middle of the desert, standing beside a car with no gas, and one says to the other: "Hey, let's pour some water in to the gas tank and ask god to turn the water into gasoline." After a brief comparison to a similar miracle performed by Jesus turning water into wine, the other missionary pours some water in to the gas tank, utters a heart-felt petition to god and viola! the car starts and they drive off to save more souls.
Many religious people have probably heard similar types of stories as this one (which should tell you something of the nature of such tall tales...). Well, in my mission a couple of sister missionaries actually tried this. One might think that this would be the perfect opportunity for god to reveal himself, and flex his supernatural muscles, but the result was exactly as one would expect if some one had poured water in to a gas tank without asking god for a miracle--not only did the car not start, but they had to send it to a mechanic for major repairs.
So, why didn't god answer the prayers of these young women who were supposedly on his errand? Surely, they demonstrated great faith, and their request would have been worthwhile by god's standard. Why such negligence from an omnipotent being who promises his faithful adherents that they can move mountains if they just believe?
In retrospect, the most interesting thing to me is not that the sister missionaries failed to receive an answer to their prayer, but how the rest of us missionaries responded to the story: belly-aching laughter. Every one of us laughed hysterically when we heard about the faux pas, and some even made misogynistic claims of the ineptitude of women behind a wheel, etc. Not a single one of us thought it would have been reasonable to expect god to answer their prayer. Why not?
The truth is, I, and many like me, are implicitly skeptical of miracle claims, if only with regards to the claims of others. I can't tell you how many times I have heard miracle claims and thought, some times aloud, "That's a little far-fetched, or just too good to be true. Why should I believe such a claim?"
Generally speaking, I think most people are pretty skeptical, if a little under-practiced. Skepticism is a skill set. It is very similar to logic, the scientific method, and the Socratic method. Each methodology has a set of fairly well-established rules which help us reduce bias and increase potential understanding. Applying these methods of thinking to our own biases and beliefs is one of the most difficult, yet most necessary forms of self improvement.
The Atheist Experience on failed prayers: