Edward Feser defends the ‘Aristotelian proof’ for the existence of God, which reasons that the only adequate explanation of the existence of change is in terms of an unchangeable, purely actual being. His argument, however, relies on the falsity of the Existential Inertia Thesis, according to which concrete objects tend to persist in existence without requiring an existential sustaining cause. In this article, I first characterize the dialectical context of Feser’s Aristotelian proof, paying special attention to EIT and its rival thesis—the Existential Expiration Thesis. Next, I provide a more precise characterization of EIT, after which I outline two metaphysical accounts of existential inertia. I then develop new lines of reasoning in favor of EIT that appeal to the theoretical virtues of explanatory power and simplicity. Finally, I address the predominant criticisms of EIT in the literature.