Marcos Antonio Norris implements Giorgio Agamben's notion of 'secularized theism' to resolve a critical disagreement among Hemingway scholars who have portrayed the writer as either a Roman Catholic or a secular existentialist. He argues that Hemingway is, properly speaking, neither a secularist nor a theist, but a 'secularised theist', whose 'religion' is practiced through sovereign decision making, which, in its most extreme form, includes the act of killing. This book resolves an important debate in Hemingway studies and uncovers fundamental similarities between theism and atheism, building upon the theoretical undertaking first introduced by Agamben and the Existentialists (EUP, 2021). Bringing Ernest Hemingway, Jean-Paul Sartre and Giorgio Agamben into close conversation, the author reconceptualises existentialism, issues a posthumanist critique of moral authoritarianism and advances an original interpretation of Hemingway as a secularised theist.