A God who acts on the world, however, allows us to ask what it is He did, how He did it, and if what it is that is being claimed for God's providence might be better explained through natural phenomena. The Shroud, whatever it is, is no older than the fourteenth century. The Shroud as evidence of God's divine providence is a testable hypothesis. It has been tested. It failed the test.
Believers claim that intercessory prayer can effect healing.
To date the handful of studies that have found positive results have been deeply flawed, such as not controlling for age, socioeconomic class, or condition of health before entering the hospital. More troubling is the impossibility of controlling for subjects in the control group receiving prayer. Such experimental controls would likely be met with derision and outright rejection. But strictly controlled prayer studies, as a testable hypothesis of God's divine intervention in our health, has failed the test. Michael Shermer has kindly granted us permission to reprint excerpts from his new book, Why We Believe.