Evolutionary argument against naturalism
In Plantinga's evolutionary argument against naturalism, he argues that the truth of evolution is an epistemic defeater for naturalism (i.e. if evolution is true, it undermines naturalism). His basic argument is that if evolution and naturalism are both true, human cognitive faculties evolved to produce beliefs that have survival value (maximizing one's success at "feeding, fighting, and reproducing"), not necessarily to produce beliefs that are true. Thus, since human cognitive faculties are tuned to survival rather than truth in the naturalism-cum-evolution model, there is reason to doubt the veracity of the products of those same faculties, including naturalism and evolution themselves. On the other hand, if God created man "in his image" by way of an evolutionary process (or any other means), then Plantinga argues our faculties would probably be reliable.
The argument does not assume any necessary correlation (or uncorrelation) between true beliefs and survival. Making the contrary assumption—that there is in fact a relatively strong correlation between truth and survival—if human belief-forming apparatus evolved giving a survival advantage, then it ought to yield truth since true beliefs confer a survival advantage. Plantinga counters that, while there may be overlap between true beliefs and beliefs that contribute to survival, the two kinds of beliefs are not the same, and he gives the following example with a man named Paul:
Perhaps Paul very much likes the idea of being eaten, but when he sees a tiger, always runs off looking for a better prospect, because he thinks it unlikely the tiger he sees will eat him. This will get his body parts in the right place so far as survival is concerned, without involving much by way of true belief... Or perhaps he thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it... Clearly there are any number of belief-cum-desire systems that equally fit a given bit of behaviour.
Naturally, there're a lot of excellent responses from critics.
In addition, one approach I might take would be to draw all sorts of uncomfortable (to him and other apologists) corollaries from his conclusion à la the Argument from Irreducible Grotesqueness (and thus disprove it by contradiction, since it it is obvious our faculties are not reliable).
But naturally he would have some even more complicated fudge for that.