In the early 18th century, Leibniz wrote Théodicée in response to the contentions of Pierre Bayle, a French religious skeptic who, among other things, maintained that reason ultimately led one astray and that a “proof” of the insufficiency of human reason was that compelling philosophical proofs could be offered which undermined the tenets of Christianity entirely – including the persistent presence of evil. Bayle averred that no rational defense could be made for the existence of evil vis-à-vis a Christian conception of god. Leibniz, however, disagreed and offered a defense of god’s existence, goodness, providence, and absolute perfection despite his seeming toleration of evil. In doing so, Leibniz introduced and coined the term theodicy, which has since referred to any attempt to vindicate god qua god in relation to evil and innocent suffering.
I have written elsewhere regarding the origins and development of religious belief from animism to monotheism, and there I stated:
“…removing the possibility of multiple deities in conflict multiplied the already existing problems for monotheism. As we have touched on previously, a singular god is either deficient or immoral (or both).”
This, in a sense, is what I like to call the “brick wall” of monotheism, i.e. that god cannot be either all-powerful or morally good – to maintain one, one must logically give up the other.
One way to try and get around this logical impediment (viz. the “brick wall”) is to try and conceive of god as an impersonal force (much like gravity). However, this route presents its own philosophical problems since implicit in the identification of god with such a force is the admission that it cannot be moral (otherwise there would be no need to reduce god to a force). If god is not morally good in any sense that is relevant to humans, then he cannot represent our highest ideal(s), which necessarily negates any worship of or devotion to him. In fact, if god is neither moral nor all-powerful, and represents no human ideal, then it begs the question: “What good is god?”
Other attempts to sidestep around such brutal moral atrocities as the Holocaust – or any intensely gruesome event marked by dark human brutality – include appeals to the divine will as “mysterious.” However, if the divine will is mysterious regarding the most violent and horrendous (i.e. most obviously immoral) of human actions, then how are we:
(a) able to claim that we understand the divine will regarding any other act, since there seems to be no prime value to anchor a moral system based on theistic beliefs, or
(b) able to look to the divine will for moral guidance in any meaningful way? If no moral guidance may be inferred from god or a belief in his existence, then what purpose can religious belief possibly serve?
This seems to be the end of theism. Any path taken in effort to solve the logical conundrums presented by monotheism only leads to contradictions, begged questions, and conclusions which directly undermine the discussion of god in the first place.