I could also eat crab meat every Thursday at 3 o'clock and if I believe strongly enough that such will heal me or help me - to some degree it will.

Consciousness is everything. Our bodies respond to our minds. Our autonomic nervous system and the sympathetic and parasympathetic branches constantly pulse intelligent energy to our organs.

The nervous system is an internet of sorts. The signals it carries will help our health or can damage it.

Stress, fear, worry all are transferred through our ten cranial nerves to the rest of our body. The signals are damaging. They throw our heartbeat out of perfect kilter, adjust our lymphatic system and release unnecessary adrenaline into our blood.

Belief and positive faith have a soothing effect. The same exact effect that some people get by visiting the doctor. Just the "act" itself and the faith in the physician and the medical establishment already sets in motion signals that can begin to heal you of your illnesses. Even dramatic "healing" or miracles can be established if enough faith is applied. It has an almost hypnotherapeutic effect. Likewise if you have no faith in your doctor and distrust the medical establishment, this can start the process of doctor shopping until one finds one within whom ones faith can be realized.

With some spittle and dirt and a rinsing in the well of Rebekah, a blind man's vision could be made whole. Jesus had little to do with the healing, other than act as a catalyst and focal point for the blind man's faith.

It's naturally a bit more complex than this rudimentary explanation, it involves fields, charges, discharges, etc. But this gives an overview as to the science behind faith healing and miracles.