Freedom of religion or belief is guaranteed in international human rights law. Incorporating the right to apostasy as a fundamental aspect of religious freedom encounters challenges in different state practices. To study this phenomenon, this article explores the interaction of the conceptualization of the right to apostasy in international human rights law and in the context of apostasy-based refugee claims. The main argument of this article is that ambiguity in international human rights law exists on the concept of ‘apostasy’. This results in human rights protection gaps when states are unwilling to grant their inhabitants the right to apostasy. These gaps in protection are sometimes filled in by refugee law. However, in the specific context of apostasy-based refugee claims, this article identifies an issue with the identification and application of the concept of apostasy—and this conceptual ambiguity may lead to a lack of protection. Indeed, conceptualization shapes practice.