The following argument has proven both interesting and vexing to many theologians and philosophers. I'd like to offer my own opinion (and what might be a fairly original argument).
The following argument gets its name from an ancient/archaic naming convention where the gist or main point of an argument is identified as the origin or starting place of the resulting conclusion (occasionally since the argument gets refined during the process).
It's also often called The Problem of Evil (as a general topic and argument name). Reprised from Mackie:
I've slightly simplified the argument so make sure to read over the great Stanford Encyclopedia of Philosophy article if you're interested. The article has a great summary of attempted refutations or replies.
The argument can be slightly reformulated into a weaker variant that targets Christian conceptions specifically.
I think it used to be the case that Plantinga’s Free Will Defense was the most widely accepted reply:
I'm not sure if this is presently the case. I want to pick apart one such formulation of the argument (setting aside other arguments or formulations). (Special thanks to Heimir Geirsson for what I consider to be the clearest, crispest, presentation of the argument - he was a great mentor to me and is an influential contributor to the whole debate!)
It establishes that in some modal logic frames, God is both present with Free Will and that the presence of Free Will cannot be present without there also being evil - the primary aim being to show that the Argument from Evil is invalid.
In other words, it’s possible that God can't create both a world in which there’s Free Will and where there is no evil.
Some personal criticisms of his argument:
We might also ask why God, given their omniscience (with a nod here to the very inspiration of such - full understanding of all possibilities - that led to modal logic semantics in the first place per Leibniz and Kripke) would choose to create such a world over one in which there is both Free Will but in which there is no evil.
Despite these criticisms, Plantinga's defense remains one of the most interesting, technically-informed, and viable defenses of theism (also one of the only ones in modern discourse) in the face of multiple attacks on various conceptions of God or the divine.
My reply. In two steps:
To draw this move out more clearly, we consult the formulation of Mackie's argument given in LaFollette's article. It concludes: "God, so described, does not exist." (on pp. 124). The theist accepts that this description does not obtain or accurately describe the relevant notion of divinity. However, the theist further maintains that such a description is irrelevant anyway.
In short, the theist can counter-intuitively accept that there is no God [no object falls under that predicate 'God'], maintaining that the relevant notion of the divine is something beyond [the concept of] God.
The First Step:
In fact, it is widely admitted by almost all major religions that this is the case (e.g. that human limitations render such conceptions as admittedly crudely and inaccurately representational).
In other words, that our human understanding of the divine is partly accurate, often not, and incomplete - that some part of God is known or knowable and the rest not or impossible to understand.
The Second Step:
The theist can rest easy and stop there having blunted the thrust of the argument. Even if the Argument from Evil is true, it's irrelevant to religious belief and divinity since 'God' is not the relevant concept anyway.
Such a move is justified by the observation above (that almost all religions and all the ones relevant for the line of attack by Mackie) accept that 'God', the 'divine', the 'almighty', etc. is unknowable (in part).
As a matter of logic, even if two properties are contradictory, their being subsumed into higher properties does not entail a further contradiction. (Simple scenario: I can't share more than one apple if I have only one apple. I can share more than one apple if I have many apples. So, lower-level property definitions being mutually exclusive or seemingly in contradiction does not entail those higher-level ones are as well.)
The theist can also move the ball forward just a bit. They can further advance the argument a tad:
Here, the theist leverages indeterminate reference (singular or not) to block the intent and main thrust of the Argument from Evil (ridding the world of a divine spark). They have not shown that there is a God (they have denied as such) but they've asserted and created the groundwork for the actual, relevant, conception (although what that amounts to remains to be seen) and can justifiably dismiss the Argument from Evil as a red-herring.
Note that 5. does not depend on the concept of 'Highest Being' and that separating these two concepts (and further refining the nature of their overlap) provides the theist with increased flexibility in resisting future attacks similar to the Argument from Evil.
The reply above should apply to the whole class of arguments (that involve the use of the word 'God').
I am not a theist - however, I see the move above as a shield to block the thrust of undue Atheism. The theist can nullify the attack of Atheism but has yet to prove the existence of God or any higher being.
Humorously, one may accept the [uh] Death of God here (meaning the end of that concept or way of talking here [LOL]) but maintain the existence of some perfectly divine being(s). This is Hegelian since it sublimates the Death of God with a repudiation of Atheism. It's also somewhat Nietzschean since this transcends the theologian's primitive notions of 'Good' and 'Evil' (as being grounded in the concept of 'God' - there is still, I think, objective morality).
See also: Supersentience.
I recently learned that Leibowitz has a similar and compelling Kantian reply.
i. The conception of God as described and used in religion/human thought.
ii. The conception of God as a noumenal object.
iii. The latter conception attempts to transcend human thinking (and results in something less than the noumenal - simply another concept) and runs afoul of common arguments against Kantian systems.
iv. I don't argue along Kantian lines and simply accept the thesis of many religions at face value - that the divine is partly or fully unknowable. That is, that the God-of-religion is not correctly captured in the theologian's vernacular in the first place.
i. The simple example described above demonstrates this: e.g. - via Cohen Forcing of a contradictory or inconsistent model to one that is model proper via extension.
ii. Consider also the Liar Paradox which I have so resolved in the same method.
Despite these differences in argumentation, we appear to agree that the Problem from Evil can be nullified - we differ in methodology, scope, and justification.