I argue that Descartes did not intend his version of the so-called ontological ‘argument’ as a formal demonstration but as a self-validating axiom, known through intuition. The claim is not that God’s existence is immediately self-evident, but rather that it can become self-evident once having dispelled one’s philosophical prejudices. Both textual and philosophical evidence for this interpretation are presented. Regarding the latter, God’s existence must be self-evident if it is to serve as the foundation for Descartes’s epistemic project. In addition, I attempt to resolve several interpretive disputes associated with Descartes’s version of the ontological argument. For example, why does he sometimes present his ‘argument’ as a syllogism if he believes that God’s existence is ultimately self-evident? Further, why does he characterize the argument as a proof from God’s essence or ‘true and immutable nature’? And why does he reverse the order of his theistic arguments from the Meditations to the Principles? Finally, it is shown how Descartes can answer many of the most important objections to the ontological argument, including the proliferation objection and the criticism that existence is not a predicate.