The last of those reasons, alongside other personal narratives in the same vein, is probably the most powerful argument against the existence of God that I've ever personally comes across. It's an argument that's put forth in various formal forms for thousands of years, mostly likely first by Epicurus in the late fourth century or early third century BC. Usually it is called argument against the existence of God from evil or the argument against the existence of God from pain and suffering. (I'll refer to both of them as the problem of pain.) While there are many ways of laying these two arguments out in a logical fashion, a little noticed aspect is that their real power comes from an appeal to emotion. Rather than being a defect, this appeal to emotion makes the arguments all the more powerful to the average individual and, as appeals to emotion, the rebuttal of these arguments so far as one exists must also be ones that tug on the heart strings rather than strictly philosophical arguments.
When the argument is laid out formally, it is unusually easy to grasp. It starts with a definition of God as a being which is both all-loving and all-powerful. If God is all-loving, the argument goes, then God will not desire that any evil or pain and suffering to occur. And if God is all-powerful, then God will not allow his desires to be frustrated. If evil or pain and suffering exist, then, God must either be unable to act on his desires, i.e. God is not all-powerful, or God is willing to let his creation suffer, i.e. God is not all-loving. And a God that lacks either of these attributes cannot, by definition, be God. The conclusion of this argument is that God has contradictory properties and, therefore, does not exist in the same way that a square circle cannot exist.
But this argument hinges on a premise that Christians rejects, that an all-loving God will not desire that evils, usually in the form of pain and suffering, befall creation. Implicit in this assertion is the idea that evils, especially pain and suffering, cannot be a force for good. But the Christian holds that some goods cannot obtain save through evil of some sort or the other. Without the fall of Adam in the Garden of Eden, there can be no nativity of Christ in the cave. Without the Crucifixion, as it were, there can be no Resurrection. So for the Christian, the problem of evil only exists if evil exists that does not lead to a greater good. The problem of evil must be qualified to really the problem of senseless evil. Does evil exist which there is no proportionately greater good?
But I suspect that many who have experienced suffering first hand, this point is rather cold comfort if, indeed, it has any meaning at all. What reason could there possibly be for God to allow the barbarity of the Holocaust? Of the ethnic cleansing in Africa and eastern Europe these past two decades? Likewise, how many victims of rape cannot would say that some good thing has come from the evil that befell them? To even think of saying to those who have experience these sorts of pain that `there is a reason this happened' seems rather inhumane and caddish. Pain and suffering of this sort offends the very conscience. To experience this sort of suffering, or even to hear of it from someone who has experienced it firsthand or to read about it in the media, brings to mind significant doubts. How is it possible that a loving God would allow these things to happen? It is easy for me to see how some reach the conclusion that a God willing to allow this to happen isn't a God worthy of worship.
Yet, it is important to note the basis on which the existence of God is being rejected. We are essentially left with one or both of two reasons. I cannot understand how this could possibly be the case so it must not be the case. I am not willing to accept that such a being as would allow these things to happen is loving. The first of these is an appeal to ignorance. The latter is an appeal to emotion. But that they are fallacious arguments from the point of view of formal logic is of no consequence to me. They are powerful arguments because to accept that God could possibly allow atrocities like these to occur and still be loving seems to run contrary to everything humanity sees as wholesome and virtuous.
And this, perhaps, is the failure of philosophy, or at least the failure of analytical philosophy. No logical demonstration of what the terms `good' and `evil' really matter to a person who experienced firsthand the horrors of a Nazi concentration camp or the murder of a loved one or the untimely death of an infant. That pain and suffering speaks to the very being of those of us who are human. If there is an answer to these doubts, it does not lie in analytic logic but in something that appeals to the same compassion and love of our consciences which are shocked by the very mention of the words `Auschwitz', `rape', `ethnic cleansing', or `Darfur'. How can it matter what conclusions are reached by analysis and logical forms if it means that there is nothing but platitudes for those who have suffered the trials of Job on top of the agony of Christ?
The only answer I can think of to this dilemma is that, in truth, if God exists then it follows that everything that has happened, everything that is happening now, and everything that will happen, does so for a reason. Admittedly, I just finished arguing that such a thought was almost an insult to those who have gone through real suffering. But we are left with one final question. If you were someone who had firsthand experienced the depths of evil, would it be better to believe that it happened for no reason or to believe that, no matter how unlikely or absurd it seems, that something good will come out of the experience? I think many people feel that it is better, more comforting, to believe that this sort of suffering happens for no reason and I cannot hold this feeling against those people who do so. It is their very compassion that leads them to that sort of conclusion. I cannot say that I can blame those who come to believe that God does not exist for these reasons.
But despite what I said above about coming off as caddish and inhumane, some people how have lived through unimaginable suffering do take comfort in the thought that no matter how wicked and filled with some events are, a reason that these particular evils have obtained exists and, somehow, these evils will result in a greater good. Whether these people do so because the alternative is even more horrifying, that there is no reason for any of it, evil just happens, or for some other reason is of no consequence. Perhaps, in some cases, these people have seen firsthand a greater good arise from the ashes of an enormous tragedy. Perhaps, in other cases, these people simply have the faith that something good must come from the evil. To argue against this point, especially with those who have greatly suffered, is no less inhumane and caddish than to try to explain away the very real sufferings to those who have lived through great suffering and reject this very point. We are dealing here, after all, with feelings and emotions that lie within the core of the soul and not with a formal argument laid out on paper.
I'm fairly certain that I've offended at least some readers by this point with my dismissal of analytic log and suggestion that an appeal to emotion could carry weight. I think those readers are making a mistake similar to the cardinal problem of modernism, mistaking empirical knowledge for all types of knowledge. They are mistaking one aspect of rationality (the ability to make analytical judgments) for all of reason. Truth, at least in the Christian tradition, is a personal relationship rather than a merely being a matter of formal analysis, syllogisms, predicate logic and the like. These latter things are certainly part of rationality and they are invaluable tools for evaluating a good deal of the world. But they are not the only tools for evaluating the world nor do they comprise rationality in its totality. To accept that to be rational, in its entirety, means to be make judgments solely on predicate logic is reduce the human person to a very one dimensional caricature of what it means to be fully human.
The best explication of what I'm getting after I've seen to date occurs in Christos Yannaras' Elements of Faith. Rather directly addressing rationality, he addresses the question of faith which so many people argue is the opposite of reason. In the context of observing how much of the modern wold sees faith as something fundamentally irrational he presents the following.
In fact, when we speak in business circles about ``faith'', we still mean the trust which a merchant inspires in marketing circles. Everyone knows him; they know his conduct and ethics of his dealings, his record of fulfilling his obligations. If he ever needs to ask for money, he will find a lender immediately, perhaps without collateral for the money which he will get, because his person and his word are sufficient guarantee.While Yannaras doesn't directly address having experiences which might make a person want to not have any sort of relationship with God, I think it relatively clear to see that his point works in both directions. We human beings are experiential creatures who tend to build our beliefs out of what (and who) we've gotten to know first hand. While there are certainly exceptions, some individuals do base their beliefs about God or the lack thereof almost entirely on this or that argument formed by predicate logic or some such tool, I assert that those exceptions are relatively rare. More often, if they are used at all, the tools of predicate logic serve to aid in coming to understand the beliefs that one has already come to as a result of various personal relationships with other people and with the world in general.
In the context of the Judeo-Christian tradition, ``faith'' functions as it does in business and in the market-place. Here the object of faith is not abstract ideas which derive their validity from some infallible authority. The object of faith is specific persons you are called upon to trust in the context of an immediate experiential relationship.
More concretely; If you believe in God, you do not do so because some theoretical principles suggest this belief to you or some foundational institution guarantees his existence. You believe him because his person, the personal experience of God, gives birth to your trust. His works and his historical ``activity'', his interventions within history, make you want a relationship with him.
In conclusion, I don't think there is any good rebuttal to the problem of pain, not because it is a logically sound argument, but because the problem is not a logical one to begin with. Rather it is a problem of conscience held by specific individual persons who have arrived at the problem through direct or indirect experience. It is a problem created by compassion and conscience that affects some, but not all, people who have directly or indirectly experienced suffering. To argue against this position only serves to make one come off as a inhumane cad. Consequently, the solution to the problem, inasmuch as there is one, is for those who would convince others of the existence of God to act in a fashion that demonstrates God's goodness. Over time, demonstrating love and compassion will heal the wounds who have had their consciences seared through their experience of suffering. This is because truth, in the final analysis, is a function of person relationships rather than a brute fact or logical form. This doesn't make belief or disbelief irrational unless one mistakes the analytic function of the psyche for the all of rationality. What it does do is serve to highlight that those who struggle with the problem of pain have compassion and a conscience and in this, the problem of pain serves to highlight our own humanity.