Empiricism v Faith

I've noticed what I believe to be a disturbing trend. It may not be anything really new, but suffice it to say things have caused me to think about it much more than in the past.
Every week at church I hear anecdotes relayed from the pulpit or from other class members or teachers. You've likely heard the format. I know A because of B. For instance: I know that tithing works because I found a 10% off coupon for school supplies that day after I paid my tithing. I know that prayer works because my illness went away after I prayed. I know that the Book of Mormon is true because I went to Mexico and saw a carving of a tree on a Mayan temple that, to me, was proof that they had heard the story of the tree of life. I know that the Book of Mormon is true because it would be far too difficult for Joseph Smith to have made all that up. All of these claims and assertions may indeed be exactly the way that their proponents claim. The problem I have with them is that they are not based on faith. All of these claims are referencing some form of "evidence". The 10% off coupon, the carving and the improved health are all evidences of the effectiveness or truth of the principle. But is this faith? I don't think so, and I think that reliance on this type of evidence based spirituality can be very disastrous. What happens if you were to loose a coupon right after paying tithing? Or what about if a child dies after being fasted and prayed over? In those cases when the evidence does not support the doctrine we tend to revert back to the real purpose of the doctrine anyway. We'll justify our faith by saying, "This is just to strengthen our faith", or "this must be God's will." It can be a serious let down if you are always looking for empirical evidences to support your faith.
Hebrews 11:1 says, “Now faith is the substance of things hoped for, the evidence of things not seen.”
Why then do so many of the faithful feel the need to justify their faith with facts?
Dr. Michael Shermer in his book How We Believe referenced a study that shed some light on this curious phenomenon. When asked why they thought other people believed a certain religion a vast majority of those surveyed responded that they probably had faith in the teaching and doctrine. Yet when asked why they personally believed a majority cited specific empirical proof like those that I have state above. Why are most of us willing to admit that others can have faith, yet when it comes to our own spirituality we feel the need to justify it with facts or evidence?
I've been thinking about this little problem for several years now and I am deeply troubled by how many people are trying to grasp the complexities of religion with their mind rather than their heart. I can speak from personal experience that continuing to use evidence as a crutch will ultimately hinder your faith. A few years ago after a long quest for evidence to support my faith I was forced to admit that if I looked any deeper then I would find more evidence that went against my faith than supported it. That is exactly what happened and I eventually had to reevaluate my testimony and discard those aspects that were based on evidence and begin to rebuild them based on faith. An added bonus to this approach is that I no longer feel the need to be defensive about the evidences to the contrary. I am content to say that I have faith that prayer works. I have faith in tithing. I have faith that the Book of Mormon and the Bible are scripture. It is actually quite liberating to not feel the need to provide evidences to support these, especially when those evidences would lead to a paradox and negate any real faith that I had in the first place.
I believe that this is exactly the lesson that Christ was teaching Thomas.
John 20:29 “Jesus saith unto him, Thomas, because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet have believed.”
Thomas was blessed for using his mind to answer the riddle of Christ's resurrection. But ultimately He praised those who used their heart above those like Thomas. There are times when it is appropriate to rely on empiricism and there are times when we're need to sit back and rely on faith. Figuring out which deserves which treatment can be the tough part, but ultimately I believe we benefit from the proper application of both.