Ever since ancient times it has occurred to many people, great and small, that the existence of evil constitutes evidence against that of God. The central claim of this thesis is that, contrary to theistic belief, this evidence is decisive. In the introduction it is argued that all previous attempts to show this fact have been unsuccessful. These attempts have been vitiated by the fallacy of supposing that God, as an all-powerful, all-knowing and all-good agent, is always required to do the best. He is capable of doing. Though other possibilities remain, this supposition usually manifested itself in arguments which claimed that a God of the above mentioned sort cannot exist, because if such a being existed, He would have created a much bett...