Abstract Philosophical atheism claims not only that there are no sufficient reasons for believing there is a God, but also that there are sufficient reasons for thinking no such deity exists. The purpose of this article is to explicate the typical commitments of this position. After distinguished several related views, the article will then consider typical grounds for the rejection of theistic commitments, first by showing that the theistic position makes a stronger claim and therefore carries the burden of proof. The article will then consider rejections of theistic attempts to shift this burden and atheist responses, including considerations of both natural and revealed theology. The intent is to present the general shape of rejections and commitments rather than proffering conclusive refutations and defenses.