It seems that God does not exist; because if one of two contraries be infinite, the other would be altogether destroyed. But the name God means that He is infinite goodness. If, therefore, God existed, there would be no evil discoverable; but there is evil in the world. Therefore, God does not exist.
Bruce R. Reichenbach seeks to defend God’s exists in the face of natural evil by appealing to a morally sufficient reason for the existence of evil. According to this view, God must have a morally sufficient reason for allowing natural evils that makes it inappropriate to assign God any blame. Reichenbach accepts the atheist’s contention that without a morally sufficient reason one could not reasonably accept the existence of an all-good and all- powerful God. Accordingly, he searches for some fact about the existence of natural evil and God’s causality of the natural world which protects God from blame and preserves his perfect goodness. To claim that natural evils are the unintended consequence of what God does intend, does not ipso facto exonerate God from culpability for their occurrence. Since God is omnipotent, he should be expected to have no limits to what he can bring about. Thus, as omnipotent, he should be able to create a world without natural evils. If such evils do occur, the morally sufficient reason that preserves God’s goodness must arise from natural evil being unavoidable. God would be free from blame for natural evils, not only because they are unintended consequences, but more importantly because they are unavoidable. Only what is logically necessary is unavoidable for God. A state of affairs is logically necessary if the description of the prevention of that state of affairs contains or entails a contradiction. Thus, for example, if God chooses and should choose a given good, and that good logically implies an accompanying evil, God is not blame-worthy for the evil. For God to choose the good but prevent the evil is a contradiction. The occurrence of the evil, in such a case, is logically necessary, and so God cannot be blamed for it. He would still be all-good, even though this evil were present in his creation. Reichenbach thus proposes a concatenation of unavoidable necessity which renders it inappropriate to blame God for the existence of natural evils. According to Reichenbach, natural evils are the unintended consequence of the world operating according to natural laws, and these natural laws, in turn, are necessary for there to be free moral agents. That God wills free moral agents is likewise necessary because a world without them is inferior to a world with them. Given that God wills to have free moral agents, then he must also will the world to operate according to natural laws, which will result in natural evils. The only alternative to a world operated by natural laws is a world operated by miracle, but such a miraculous world would not allow for the existence of free moral agents and a significant exercise of their freedom. Reichenbach’s theodicy thus hangs on this chain of necessity which holds God to having to allow natural evils in order to have free moral agents, which he is also bound to do. Reichenbach gives two reasons for the impossibility of God creating free moral agents in a world operated my miracle. First, deliberation, a necessary condition for the exercise of rational choice, is prohibited given the confusion and unpredictability of a world operated by miracle. Moral action requires rational deliberation on the best means to attaining one’s desired end. However, if the world does not operate according to any regularity, but only according to the caprice of divine will, then a moral agent has no way to anticipate which means are likely to bring about which ends. Moral action is thus thwarted because rational knowledge is impossible. http://www.aquinasonline.com/Topics/probevil.html.