Does God exist? Most people today would probably regard this question as having great existential import, but as one to which rational arguments are irrelevant. But historically, this has not been the case. Ever since Plato, great thinkers have, until recently, regarded this as an issue central to rational philosophical inquiry, and they sought to prove or to disprove to the best of their ability that God exists. In this book, I seek to examine one particular proof for the existence of God: