The standard objection to fundamentalism---that family of views according to which certain propositions are believed to be revealed by God and ipso facto to have complete epistemic authority---is, roughly speaking, that it is unreasonable because it so often conflicts with our best evidence. In this dissertation, I focus on a prominent case of fundamentalism, young-earth creationism (YEC), the view that the entire cosmos was created by God less than 10,000 years ago. I argue that the standard objection to YEC is superficial, dogmatic, and incomplete, and I offer a modified objection to YEC that attempts to overcome these problems. The modified objection is less superficial in that it empathetically describes the logic and epistemology of YEC on its own terms and in its best light. The modified objection is less dogmatic in that it does not depend on any Archimedean point of rationality or global epistemic frame of reference when criticizing YEC. Rather, I focus on YEC's alethic goal---to maximize truth and minimize error---and its doxological goal---to lead people to worship the true God---and attempt to show how these goals are inconsistent with YEC's theoretical assumptions. This approach raises neglected questions and allows for a more complete objection to YEC. Specifically, I argue that given YEC's assumption of hermeneutical nonconformism---the view that for any biblical claim p, no extra-biblical claim q, regardless of how likely it is on the evidence that q is true, can force a figurative, instead of literal, interpretation of p---YEC fails to meet its own alethic and doxological goals. Next, I argue that YEC further fails to meet these goals given its non-evidentialist justification for its propositional revelation doctrine---the view (roughly) that YEC was revealed by God. I then consider a previously unexplored nondoxastic conception of the nature of propositional faith that young-earth creationists could take in response to the standard objection as well as to my modified objection. I conclude by briefly showing how the approach I take with YEC could be applied to other instantiations of fundamentalism, e.g., Islamic extremism as exemplified by Al-Qaeda.