Who is the God in whom Christians believe? Is he just a figment of the human mind as critics of religion claimed in the nineteenth century and as crusading atheists assert again today? Since the beginnings of rational thought the brightest minds among humanity have attempted to assert that God does indeed exist. But even the so-called proofs for God’s existence always started with the assumption that there is someone to prove. As soon as we move beyond that which is within space and time mere proofs or disproofs no longer suffice. Both believers and unbelievers live to a certain degree by faith. Yet religion is inextricably connected with human history. When we journey through the landscape of religion and witness its gradual unfolding we soon realize that not all religions are equal. Though they may be witnesses of the same God, the way they talk about God is so different that this not only leads to very different concepts of God but also to different approaches to life on this earth. At the end of this long journey we finally arrive at the Judeo-Christian tradition which witnesses to the God in whom Christians believe. This book seeks to show how this belief matured and what difference this belief still makes today.