I have talked with many skeptics who claim that they do not believe in God because he has not conclusively demonstrated his existence to them. When asked how God might demonstrate his existence to their satisfaction I usually get an answer that consists of some criteria in which God would do something so spectacular that his intervention could not be denied. A classic example is that if God would miraculously regrow the limb of an amputee then the skeptic would believe in God. I addressed this issue to some extent in my post titled "
Extraordinary Claims and Extraordinary Evidence." I personally don't think that even such an extraordinary event would convince most skeptics of the existence of God. Would they actually have to see the limb as it grows back? Would they accept that the limb had grown back miraculously if a number of people including the person's doctor claimed that the limb was gone and now it is back?
Suppose I was to propose an experiment to test for God in which 1000 people prayed that a miracle would occur. Would that be a valid test for the existence of God? Actually, from a scientific perspective that could not, even in principle, be a valid test regardless of the results, either positive or negative, and could not be scientifically accepted. In any test involving a person with volition and the ability to make choices, the test is considered biased and invalid if the person knows she is being observed and can change her behavior to influence the test. In any test of God, he would know he is being tested and could change his behavior to influence the test. Consequently, regardless of the outcome of the test, it would be considered scientifically invalid.
