Antony Flew shows the Freewill Defense theodicy fails since it is the case that existence of compatibilist free will is not a logical impossibility relative to what is generally thought of as Omnipotence in his essay “Divine Omnipotence and Human Freewill” featured in Peter Angeles' anthology, “Critiques of God”.
Flew begins by wrongfully, but inconsequentially so since many falsely think the following to be from Augustine’s “Confessions”, quoting  St Augustine : "Either God cannot abolish evil, or he will not; if he cannot, then he is not all-powerful; if he will not, then he is not all good."  An elegant summation nonetheless, Flew rightly pigeon holed the saying by noting that this is “Perhaps the most powerful of all skeptical arguments, this has appealed especially to the clearest and most direct minds, striking straight and decisively to the heart of the matter.” Actual EVIL, existing in contradistinction to actual moral goodness, is the substantive core of the question at issue. How can the God of classical theism exist when the world, and even more so the Universe (ie: all existence), is saturated with a cold indifference to life? Not only does observed empirical existence reveal man’s inhumanity to man, but the unimaginable sickening horror from natural disasters evidenced by an ever growing list of causalities dimly echoes within a grand canyon of animal suffering. The predator-prey and parasite-host relationships in a brutally uncaring, mechanistic, evolutionary context screams “Humans are not the point.”
In large measure, the history of human civilization has been recorded in step with efforts to understand our existence. By crafting myths, we encode ways we try to reconcile seeming contradictions between life and brutal reality. Such is the case of the world's oldest story. When Gilgamesh, the king, sends the woman Shamhat, a temple prostitute, to Enkidu, the wild-man, their sexual liaison civilizes Enkidu. After six days and seven nights of love making, he is no longer a wild beast who lives with animals.  Upon visiting the water hole, the animals flee from the sight of Enkidu, puzzled he asks Shamhat what it means. She wisely informs the anti-hero, “Behold Enkidu, you are become wise like unto a god.”  As the knowledge of sexual procreation transformed the wild Enkidu, we ordinary mortals, when we become aware of the absolute nature of existence and its identity, become transformed by recognizing that objective good arises from objective existence while evils anticipates a dearth of goodness. While these ethical qualities share a relationship like up and down or big and small, good and evil are nonetheless objective. And, even though, mutually required to make sense of the other, they can be understood in light of what is meant by values and why they are important to living beings. The Objectivist philosophers offer clear and cogent definitions.
“In ethics, one must begin by asking: What are values? Why does man need them?” Wrote Ayn Rand, and she continued: “Value” is that which one acts to gain and/or keep. The concept “value” is not a primary; it presupposes an answer to the question: of value to whom and for what? It presupposes an entity capable of acting to achieve a goal in the face of an alternative. Where no alternative exists, no goals and no values are possible.
I quote from Galt’s speech: “There is only one fundamental alternative in the universe: existence or nonexistence—and it pertains to a single class of entities: to living organisms. The existence of inanimate matter is unconditional, the existence of life is not: it depends on a specific course of action. Matter is indestructible, it changes its forms, but it cannot cease to exist. It is only a living organism that faces a constant alternative: the issue of life or death. Life is a process of self-sustaining and self-generated action. If an organism fails in that action, it dies; its chemical elements remain, but its life goes out of existence. It is only the concept of ‘Life’ that makes the concept of ‘Value’ possible. It is only to a living entity that things can be good or evil.” 
Even so, the broad scope of animal suffering, a vast ocean of pain and terror, is like the Great Barrier Reef of objective evil, for if anything diminishes the “process of self-sustaining and self-generated action”, it is the pain, suffering, and terror of being eaten or burned alive. “Suppose in some distant forest lightning strikes a dead tree,” wrote William L. Rowe in describing the problem of evil: “resulting in a forest fire. In the fire a fawn is trapped, horribly burned, and lies in terrible agony for several days before death relieves its suffering. So far as we can see, the fawn's suffering is pointless. For there does not appear to be any greater good such that the prevention of the fawn's suffering would require either the loss of that good or the occurrence of an evil equally bad or worse. Nor does there seem to be any equally bad or worse evil so connected to the fawn's suffering that it would have had to occur had the fawn;s suffering been prevented. Could an omnipotent, omniscient being have prevented the fawn's apparently pointless suffering? The answer is obvious, as even the theist will insist, An omnipotent, omniscient being could have easily prevented the fawn from being horribly burned, or, given the burning, could have spared the fawn the intense suffering by quickly ending its life, rather that allowing the fawn to lie in terrible agony for several days. Since the fawn's intense suffering was preventable and so far as we can see, pointless, doesn't it appear that premise one (See note 6.) of the argument is true, that there do exist instances of intense suffering which an omnipotent, omniscient being could have prevented without thereby losing some greater good or permitting some evil equally bad or worse? 
There is a problem of evil, and we recognize it concurrently with our awareness of objective morality from absolute existence. Perhaps that may be why Flew found it useful to cite John S. Mill’s posthumously published “Three Essays on Religion” to further refine the problem and challenge theology by noting Mill did not imagine “the impossible problem of reconciling infinite benevolence and justice with infinite power in the Creator of such a world as this. The attempt to do so not only involves absolute contradiction in an intellectual point of view but exhibits to excess the revolting spectacle of a jesuitical defense of moral enormities.”  Amen! Mill’s bold words are, however, not conclusive, for the Christian believer has faith that ways to reconcile the existence of objective evil with their God’s omni-loving, omni-compassion attributes can be found.
For that purpose theodicies have been devised. Flew notes that: “Several determined efforts have been made to escape from the dilemma. One favorite – which might be dubbed the ‘Freewill Defense’ – runs like this. The first move is to point out ,via citing Thomas Aquinas, “Nothing which implies contradiction falls under the omnipotence of God.”  Flew elucidates, “even God cannot do what is logically impossible; that is, if you make up a self-contradictory, a nonsense sentence it won’t miraculously become sense just because you have put the word God as its subject.” Flew follows up on this by predicating that theologians find the third formulation superior because it pinpoints the essential quality of logical impossibility as being no restriction upon the Omnipotence of God. Antony rightly disagrees with Aquinas, however, that God’s Omnipotence is indeed limited by logical impossibility. Flew could have pointed out that the forth and fifth century superstars of Christian Theology, St. Augustine,  and St. Jerome  both disagreed with Aquinas and implicitly asserted that God being all powerful means God can do anything without regard to logic. How or why the Christian view of Omnipotence evolved in the centuries between Jerome and Aquinas Flew does not ask, but it would be an interesting study.
He could have followed that thread down a rabbit hole. Instead, and to his credit, he continued to state the position he argues against. “The second move in this defense is to claim, “God gave men free will”; and that this necessarily implies the possibility of doing evil as well as good, that is to say, that there would be a contradiction speaking, it would be nonsense to speak of creatures with freedom to choose good or evil but not able to choose evil. (Which, no blame to him, is what his creatures, men have done.)”  Generally, Christians will not seek to specify the nature of free will and will equivocate by assuming it is understood that they mean contra-causal libertarian free will.
Antony could have, but did not, include the scriptural proof texts Christians predicate as a basis for their contra-causal and libertarian view of free will. It is interesting that the Johannine writer’s midrash in John 10:34-35 “Jesus answered them, "Is it not written in your law, 'I said, you are gods'? If he called them gods to whom the word of God came (and scripture cannot be broken),” refers back to Psa 82:6 where is read: “I say, "You are gods, sons of the Most High, all of you;” . In the later passage, Elohiym is in the council of the elohiym and is exhorting his fellow gods to do justice and righteousness; and then in a fit of hissy, Elohiym condemns his fellow gods to mortality. Elohiym, in 82:6, is very clearly addressing his fellows in the council of the gods. The Johannine midrash tortures the text to make it apply to human beings (ie: the Jews). A truly brilliant man, Richard Carrier, explains what this means to Christianity. “...the Libertarian notion of free will assumes that one's own desires (among other things, like one's own reason and knowledge) also constrain one's will, rendering it unfree. In other words, our personality, knowledge, wishes, are themselves chains that bind our will. But your proximate, causing desire is your will. It therefore cannot be considered as something “outside” of the will that constrains it – your strongest desire and your will are one and the same.”  Later, as we will see, Flew’s argument hinges on the fact that human free will is not Libertarian.
The third premise of the free will defense listed by Flew is: “…certain good things, namely, certain virtues, logically presuppose not merely beings with freedom of choice (which alone are capable of either virtue or vice), and consequently the possibility of evil, but also the actual occurrence of certain evils. That what we might call the second-order goods of sympathetic feeling and action logically could not occur with out (at least the appearance of) the first-order evils of suffering or misfortune. And the moral good of forgiveness presupposes the prior occurrence of (at least the appearance of) some lower-order moral evil to be forgiven.”  Flew goes on to elaborate and explain this premise by noting the subjective nature of good and evil assumed by the F.W.D. Certain moral virtues “logically presuppose the possibility of correlative evils”  This leads to the conclusion that it “makes no sense to suppose that God “might have chosen to achieve these goods without the possibility in the one case, the actuality in the other of the correlative and presupposed evils.”  Flew's acceptance of subjective definitions of good and evil is contrary to Objectivism; that notwithstanding, his argument still has value to those humans who seek to live and thus make a conscious choice not to lie down and die. (It is beyond the scope to this brief essay, however, to show how Flew and Objectivism can be harmonized.)
Antony assesses the argument as disconcerting to the skeptic, and yet he excuses the usual counter arguments as lacking simplicity or a decisive presence compared to the original dilemma in that they allow the believer room to counter argue. Having set up a dissonance, in dialectical fashion, he then offers a penetrating foil towards coherent synthesis. His attack is directed at the central idea of the F.W.D.; it would be fatal to the notion of the Christian God that if it were not the case that a contradiction obtains such that God could not create a free will where people always choose to do the good. If it is logically possible for God to make a free will that is truly free and also determined so that people always freely choose to do good, then Omnipotence could have “made a world inhabited by wholly virtuous people.” Then the F.W.D. collapses, and the problem of evil destroys any reasoned basis for God belief.
This idea is reinforced by Raymond D. Bradley, who argued from international criminal law: “according to the moral principles concerning Command Responsibility as recognized by Ping Fa around 500 B.C.E., principles that were eventually enshrined in the Hague Conventions of 1907, the Geneva Conventions of 1948, and the Nuremberg Charter of 1950 (Principles III and VI of which explicitly assign responsibility to Heads of State who have "planned" and "initiated" crimes against humanity). And, quoting from Article 7 (3) of the International Criminal Tribunal for the former Yugoslavia, they pointed out that the fact that a subordinate committed crimes does not relieve his superior of criminal responsibility if he knew or had reason to know that the subordinate was about to commit such acts or had done so and the superior failed to take the necessary and reasonable measures to prevent such acts. This principle, they observed, is a particular instance of the more general moral truth:
If a person knows that evil of any kind (natural or moral) will occur or continue to occur unless they prevent it from occurring, and has the ability to prevent it from occurring, then that person is morally culpable for the occurrence of that evil. By virtue of his omnipotence and omniscience, God was found to be an accessory, before, during, and after, the fact of all evils.” 
This sets the stage for Flew's blitzkrieg. The first pincer entails defining what it means to act freely. He asks what is meant by “being free to choose”? His insight is that being free to choose does not necessarily mean the choice is unpredictable or uncaused. Paradigmatically, he spins a touching tale about two young lovers with nothing better to do than get married. Murdo exercised his freedom by asking his love, Mairi. Being madly in love with Murdo, she gladly acquiesced. Murdo's and Mairi's actions were not uncaused or in principle unpredictable, nor were they compelled. Yet even if in an all too near future, it becomes a predictable norm that such pairings or nascent behaviors are completely predictable , still Homo Sapiens will be able to choose to do what they want. They will still be able to choose between alternatives that are most appealing. Flew argues that “Unless they (advocates of hard determinism) produce evidence that there was obstruction or pressure or an absence of alternatives, their discoveries will not even be relevant to questions about his freedom of choice, much less a decisive disproof of the manifest fact that sometimes he has complete, sometimes restricted, and sometimes no freedom.” 
When we use expressions that characterize an action as either freely chosen or compelled in some fashion, we are not saying that what was done was in theory unpredictable and neither are we asserting that the action was contra-casual. But we are saying that there were viable alternatives. Pivoting on the phrase “could have helped it”, Flew explains that by examining simple “paradigm” cases where writers freely choose from a variety of lexical tools to craft their missives, we can find a wealth of examples of free actions. And if not, then they'll do till the real thing comes along.
Flew's prophecy was fulfilled. Behold - brilliance. “Even if my choices are entirely determined in advance,” expounded Dr. Richard Carrier regarding what free will actually means: “I still make decisions, and my decisions are still caused by who I am and what I know – my thoughts and desires and personality - just as they must be if I am to be “free” in any sense that matters. And because I am still their cause, I can still be praised or blamed for them. This is why compatibilism makes more sense: free will is doing what you want – nothing more, nothing less. And being responsible is being the cause - nothing more, nothing less.”]
Plop-plop-fizz-fizz goes the cathode! After such crafty word smithy, for Flew to just pour his premise like Alka-Seltzer is almost anti-climatic, yet soothing. “...there is no contradiction involved in saying that a particular action or choice was: both free, and could have been helped, and so on; and predictable, or even foreknown, and explicable in terms of caused causes.” He admits that he cannot here demonstrate the premise sound, but he does note that Hume, Hobbes and even Aristotle took a similar line of reasoning. Meanwhile back at the anode, the Catholic Church predicates that it's God has foreknowledge that is not incompatible with human freedom. Raising the bet, he turns the kicker and amusingly observes that, if compatibilism is error, then human free will hitch hikes on God of the Gaps arguments and like God hides in human ignorance. Flew's spartan rhetorical question polishes the first pincer. “... if it is wrong, then it is hard to see what meaning those expressions (“could have helped it”) have and how if at all they could ever be taught, understood, or correctly used.”
Having saved his Panzer divisions, he now deploys them into the other pincer and closes on the salient. “... not only is there no necessary conflict between acting freely and behaving predictably and/or as a result of caused causes; but also Omnipotence might have, could without contradiction be said to have, created only people who would have already as a matter of fact freely have chosen to do the right thing.”  Observing that a person's endocrine glands are not the same as a person, and that whatever physiological cause may be accorded responsible for a person's action, it is not contradictory to say that if people can sometimes help doing what they do, they still act freely. He argues against the objection that physiological causes of actions exclude the possibility of doing what is desired. Emphasizing that the absence of proposed physiological causation would imply absence of effect, he contra-distinguishes mental motives to accent a disconnect between the two. By way of analogy he points out that “... if I think as I do because of such and such physiological causes or because of such and such motives; then it cannot also be the case that there are, and I have sufficient reasons, arguments, grounds for thinking as I do.” This hinges on how “because” equivocates multiple ambiguities. There are many explanations which do not exclude one another.
Carrier speaks to the fallacy here identified by Flew when he argues in defense of compatibilism against J.P. Moreland. “Moreland says, for example, that on compatibilism “a reason for acting turns out to be a certain type of state in the agent, a belief-desire state, that is a real efficient cause of the action”. He (Moreland) argues this excludes the possibility of final causes. But since a belief-desire state is an intention, and an intention is a final cause, it follows that final causes can and do exist under compatibilism. A final cause is simply a thought process: a prior calculation form ends to means, which in turn participates in the causal chain that ends in acting. The visualized 'end' is caused by a desire (“I want the second ball to land in the corner pocket”), and the conceptualization of the 'means' is caused by an application of reason and knowledge to that desired end (“If I collide the first ball into the second just so, then I will achieve what I want”). That is all a final cause is, a thought process, and that's an efficient cause: without the final cause (the desired end) there would be no act. So Moreland is attempting to state a tautology (A is B) as if it were a distinction (A is not B), a fundamental violation of basic logic.”  The same fallacy was committed by those determinists Flew argued against who claimed physiological causes precluded mental motives. If it is objected that Murdo and Mairi were influence by their glands, again it is pointed out that glands are not people. Murdo and Mairi made their own decision. Despite this it is also true that we can do what we want but that we cannot want whatever we want.
At this point in his essay, Flew serves the 800 pound Gorilla. What becomes of the keystone of the Freewill Defense, if there does not exist a contradiction in thinking that God could have arranged things so that human beings always freely choose the good? If it really is possible for a person's action to be freely chosen and fully determined by caused causes, then doesn't the theodicy collapse? All goods of whatever order presuppose not only corresponding lower order evils but also freedom. Even virtues like honesty and intellectual integrity while not parasitic upon antecedent evils are still contingent to freedom. If there is no contradiction, then there is no need for any soul making theodicy either. The resultant people, no matter the challenge, would always choose the right without the evils of those who choose damnation or that required for higher order goods and virtues. The deity could have evolved humans trustworthy in all situations without need for acquiring trustworthiness via fortitude, suffering, or pain. However, in that case it would be senseless to suggest that God would still be required to forgive or display fortitude.
Nonetheless, subtly reworded versions of Predestination or Determinism could be hurled at the argument. “...but that there is not contradiction in speaking of a world in which there are always antecedent conditions of all human action sufficient to ensure that agents always will as a matter of fact freely chose the right.”  The distinction turns on crucial differences in the character of the deity. If the former is asserted, then God's character would be that of a quasi-personal being that has fixed everything that everyone will do, choose, and suffer. If the latter, then the deity is not thought of a puppet master or master hypnotist, rather it just happens to be the case that antecedent conditions predisposing humans to act in a particular, instead of some other, fashion always have, do, and will always obtain. The counter thesis would specify that determinism is perhaps compatible with human freedom and responsibility, but that predestination is assuredly not.
The error here is that predestination alleviates all human responsibility no matter what. Flew wrote: “The first reaction to the idea of God, the Great Hypnotist, is that this would mean that no one ever was or had been or would be really responsible, that none of the people who we should otherwise have been certain could have helped doing things really could. ... But this is very misleading. Certainly it would be monstrous to suggest that anyone, however truly responsible to and in the eyes of men, could fairly be called to account and be punished by the 'God who had rigged his every move. All the bitter words which have ever been written against the wickedness of the God of predestinationism – especially when he is also thought of as filling Hell with all but the elect – are amply justified.”  By reminding the reader that the paradigmatic cases defining key phrases exemplifying human liberty are impervious to the predestination doctrine as no theological information can alter their meaning, Flew counters the objection.
Refining the position: “...there is no contradiction in speaking of God as so arranging the laws of nature that all men always as a matter of fact freely choose to do the right.” What infuriates is still the idea that providence punishes anyone for freely choosing the wrong in the case that omnipotence had arraigned the antecedent conditions so that his victim would so act. Flew concludes: “...the Calvinist picture – the Great Hypnotist – is appropriate in its appreciation of the implications of Omnipotence; it is morally obnoxious insofar as it presents human creatures justly accountable to that Omnipotence.” 
Flew couldn't resist his sense of symmetry. Although his free choice was likely determined, still he wrote what he wanted, and that's compatibilist free will. As it was in the beginning, so he closes. "Either God cannot abolish evil, or he will not; if he cannot, then he is not all-powerful; if he will not, then he is not all good."
 Anthony Flew, ‘Divine Omnipotence and Human Freedom’, p.227, in “Critiques of God: A major statement of the case against belief in God”, edited by Peter Angeles, copyright 1976.
 Flew acknowledged his error in wrongly attributing the given quotation to St. Augustine, and he thanked Dr. John Burnaby of St. John’s College for pointing out that St. Augustine did not write the line. The author of the present essay was unsuccessful in finding the actual source of the quote.
 Dr. Robert Price makes this point in his Bilbegeek Genesis #2 podcast.
 Ayn Rand, 'The Objectivist Ethics,' p.15, in “The Virtue of Selfishness”
 William L. Rowe, 'The Problem of Evil and Some Varieties of Atheism', p.253, in “The Improbability of God”, edited by Michael Martin and Ricki Monnier
(Premise 1. “There exist instances of intense suffering which an omnipotent, omniscient being could have prevented without thereby losing some greater good or permitting some evil equally bad or worse.”
Premise 2. “An omniscient, wholly good being would prevent the occurrence of any intense suffering it could, unless it could not do so without thereby losing some greater good or permitting some evil equally bad or worse.”) - quoted from Rowe, ibid., p.251
 John S. Mill, “Three Essays on Religion”, p.186-87 as quoted by Flew, ibid. p.228
 Flew, ibid. p.228 citing Aquinas from “Summa Theologica”, IA XXV, Art. 4.
 St. Augustine, “…for certainly He is called Almighty only because He is mighty to do all He will…”; “City of God”, Book XXI, p.458, “NPNF1-02. St. Augustin's City of God and Christian Doctrine” - http://www.ccel.org/ccel/schaff/npnf102/Page_458.html
 St. Jerome, “But I do not presume to limit God's omnipotence…”; “EPISTLE 58: TO PAULINUS”, Art. 3, - http://www.voskrese.info/spl/jerome058.html
 Flew, ibid. p.228
 Richard Carrier, “Sense and Goodness Without God: A Defense of Metaphysical Naturalism”, p.109
 Flew, ibid. p.228
 ibid. p.229
 ibid. p.229
 ibid. p.229
 Flew, ibid. p.230
 Carrier, ibid., p.109
 Flew, ibid., p.231
 Carrier, ibid., p.107
 Flew, ibid., p.233
 ibid., p.235; “The recognition, for example, of the object of highest worship in a being who could make a Hell; and who could create countless generations of human being with the certain foreknowledge that he was creating them for this fate ... Any other of the outrages to the most ordinary justice and humanity involved in the common Christian conception of the moral character of God sinks into insignificance beside this dreadful idealization of wickedness.” (quoted from Mills, “Three Essays On Religion”, p.113-14)
 ibid., p.235