A. The atheistic argument from evil clearly relies on our knowledge of what a good/loving God would or would not (might or might not) do. There are two obvious problems:
A. Theists should reject the question, "Why did God create evil?" God didn't create evil, because evil is not a positive existence in its own right. Evil consists simply in the absence of a particular good. This is the so-called privative theory of evil.
B.H owever, we can still ask the question, why did God not cause or create more good? Nonetheless, this second question may have no interesting answer. God may have had no reason not to do certain things He did not in fact do. He may simply have chosen freely not to do those things. To demand that God must have a reason for not doing anything He does not do is to assume the Principle of Sufficient Reason, and to assume, in fact, that whatever happens happens by necessity. In contrast, to insist that God must have a reason for doing everything (positive) that He does, is simply to assume that God is rational and purposeful.
A. God is perfect, and evil is a privation, so God cannot be evil. Moral evil is the absence of some possible good, such as wisdom, love or self-control. God cannot lack any possible good, so God cannot be evil in any respect.B.The Platonistic Argument (Aquinas's Fourth Way)
God is identical to the property of goodness itself. There must be such a property, since good things do exist. Since God is the first cause of all good things, God must be good Himself. Since God is absolutely simple, God is identical to His own essence. Hence, God is identical to His own goodness. Since God is the first cause, God's goodness is the universal form of goodness. Therefore, God is identical to the property of goodness itself. The property of goodness must be perfectly good. Thus, God is perfectly good.
C. The Explanation of our Moral Knowledge
If we suppose the God is perfectly good, this hypothesis can be used to explain how it is that we have moral knowledge. A perfectly good God would both know all moral truths and desire to share that knowledge with all rational creatures. Hence, we can expect that a perfectly good God would have created us with an innate disposition toward reliable knowledge of moral truth. If God were not morally good, either because He lacked moral insight or because He lacked good will, we would have no explanation of how we, His creatures, came to have reliable moral knowledge.
D. The Asymmetry of Good and Evil
If God were a mixture of good and evil, then the two would have an equal footing in reality. Nonetheless, it seems that there is a fundamental asymmetry between the two, and this asymmetry must have its root in God's character. The simplest explanation of this asymmetry would be to posit that God is wholly good and utterly lacking in evil
A. Thinking about God's goodness brings us back to another issue we have discussed before: the issue of nominalism versus realism. If we are nominalists, then to say that God is good is to say that God's character and motivation resemble those of a paradigmatically good human being. In contrast, if we are realists, then to say that God is good is simply to attribute to God the very same property possessed by good human beings, the very property that makes good human beings good. This property of goodness may express itself very differently, depending on the nature of the bearer.
B. Since God and human creatures have radically different natures, God being infinite and necessary, human creatures being finite and wholly contingent, God's goodness can amount in practice to something quite different from human goodness. This makes it much more difficult to argue a priori from God's actions to the state of God's character (in other words, to learn what a good God might do, we have to actually look and see what a good God has done.) It also makes it difficult to reason from God's goodnessto specific actions or inactions.
C. Nonetheless, we are not left in a state of complete agnosticism about God's moral qualities. First of all, we may be able to find a priori, metaphysical arguments for or against God's goodness, that are independent of an evaluation of God's actual behavior. Second, we can reason more confidently about God's actions whenever God voluntarily takes on a role that bears great similarity to the social roles of human beings. For example, if God deigns to use human language, God's speech acts are very similar to our own, and moral principles about truth-telling would presumably apply to God's speech as well as to our own. Similarly, if God enters into a practice of treaty-making or promise-keeping, the moral norms governing those practices would apply to God's actions. In contrast, God's act of creating and sustaining the cosmos is radically dissimilar to any human action, and, consequently, we should be very diffident about applying human norms to these actions.
D. The problem of devil worship. If we admit that God's goodness may be radically different from our own, how does worshipping such a God differ from worshipping an omnipotent devil?
The difference is simple: God is actually good, and the devil is not. Although we may not be able to work out operationally or in practice what God's goodness means, we are still insisting (as realists) that God possesses (in an infinite form) the very property of goodness we admire in other humans and aspire to ourselves.
E. The relevance of salvation history and the Incarnation.
Insofar as God accommodates Himself to our natures by entering into covenants with human beings, He acts in such a way as to be subject to ordinary human moral judgments. When God acts like a king or oriental potentate, ratifying a treaty or testament with us, we can be sure that He will act like a good king: that He will keep His promises, that He will exercise judgment without partiality or corruption.