Alvin Plantinga (who was born in 1932 in Ann Arbor, Michigan, and started his teaching career at my alma mater, Wayne State University, in Detroit) is widely considered — by his Christian or theist admirers and atheists alike — to be the greatest living Christian philosopher and philosopher of religion.
He wrote a very influential book in 1974, called God, Freedom, and Evil (Grand Rapids: Eerdmans / New York: Harper & Row), which is now widely regarded as the best (and indeed, a decisive) refutation of the atheist use of the classic “Logical Problem of Evil” in order to disprove God’s existence, or (if not His existence) His character as all-good and all-powerful, since (so it claims) that Christian belief involves an inherent contradiction therein.
From: Warranted Christian Belief (Oxford University Press, 2000):
[S]uppose evil does constitute evidence of some kind against theism: what follows form that? Not much. . . . Is the idea, instead, that the existence of God is improbable with respect to our total evidence, all the rest of what we know or believe? To show this, the atheologian would have to look into all the evidence for the existence of God — the traditional ontological, cosmological, and teleological arguments, as well as many others; he would be obliged to weigh the relative merits of all these arguments, and weigh them against the evidential argument from evil in order to reach the indicated conclusion. This is vastly messier and more problematic than a terse and elegant demonstration of contradiction à la Mackie. (pp. 462-463)
Suppose the fact is God has a reason for permitting a particular evil like E1 or E2, and suppose we try to figure out what that reason might be: is it likely that we would come up with the right answer? Is it even likely that we would wind up with plausible candidates for God’s reason? A series of important recent papers by Stephen Wykstra, William Alston, and Peter van Inwagen argue (among other things) that it is not. The main reason is the epistemic distance between us and God: given that God does have a reason for permitting these evils, why think we would be the first to know? Given that he is omniscient and given our very substantial epistemic limitations, it isn’t at all surprising that his reasons for some of what he does or permits completely escape us. But then from the fact that no goods we know of are such that we know that they justify God in (serve as his reasons for) permitting E1 or E2, it simply doesn’t follow that it is probable, with respect to what we know, that there aren’t any such goods, or that God has no reason for permitting those evils. The arguments in those papers seem to me to be conclusive; I shall not repeat them here. (pp. 466-467)
[Plantinga later argues that the book of Job in the Bible provides a pre-philosophical version of the same sort of argument]:
Job’s problem is really intellectual; he can’t see any reason at all why God should allow him to be afflicted as he is; and he is inclined to conclude, unthinkingly, that probably God doesn’t have a good reason. The point here is that the reason for Job’s sufferings is something entirely beyond his knowledge or awareness; but then the fact that he can’t see what sort of reason God might have for permitting his suffering doesn’t even tend to suggest that God has no reason. And when God replies to Job, he doesn’t tell him what his reason is for permitting these sufferings (perhaps Job couldn’t so much as grasp or comprehend it). Instead, he attacks the implicit inference from Job’s not being able to see what God’s reason is to the notion that probably he has none; he does this by pointing out how vast is the gulf between Job’s knowledge and God’s:
[Plantinga then cites Job 38:1-7, 16-21 in an unspecified Bible version. I shall cite my favored RSV, so I can quickly cut-and-paste]:
 Then the LORD answered Job out of the whirlwind:
 “Who is this that darkens counsel by words without knowledge?
 Gird up your loins like a man,
I will question you, and you shall declare to me.
 “Where were you when I laid the foundation of the earth?
Tell me, if you have understanding.
 Who determined its measurements — surely you know!
Or who stretched the line upon it?
 On what were its bases sunk,
or who laid its cornerstone,
 when the morning stars sang together,
and all the sons of God shouted for joy?
[. . .]
 “Have you entered into the springs of the sea,
or walked in the recesses of the deep?
 Have the gates of death been revealed to you,
or have you seen the gates of deep darkness?
 Have you comprehended the expanse of the earth?
Declare, if you know all this.
 “Where is the way to the dwelling of light,
and where is the place of darkness,
 that you may take it to its territory
and that you may discern the paths to its home?
 You know, for you were born then,
and the number of your days is great!
Job complains that God apparently has no good reason for permitting the evil that befalls him. He suspects that God doesn’t have a good reason because he, Job, can’t imagine what that reason might be. In reply, God does not tell him what the reason is; instead, he attacks Job’s unthinking assumption that if he, Job, can’t imagine what reason God might have, then probably God doesn’t have a reason at all. And God attacks this assumption by pointing out how limited Job’s knowledge is along these lines. No doubt he can’t see what God’s reason might be, but nothing of interest follows form this: in particular it doesn’t follow that probably God doesn’t have a reason. “All right, Job, if you’re so smart, if you know so much, tell me about it! Tell me how the universe was created; tell me about the sons of God who shouted with joy upon its creation! No doubt you were there!” And Job sees the point: “I have spoken of great things which I have not understood, things too wonderful for me to know” (42:3). (pp. 496-497)
[or, in RSV: “Therefore I have uttered what I did not understand, things too wonderful for me, which I did not know.”]
Photo credit: Job and His Friends (1869), by Ilya Repin (1844-1930) [public domain / Wikimedia Commons]