The very influential theoretical concepts proposed by Rudolf Otto in his 1917 classic The Idea of the Holy are often seen as examples of properly religious content that cannot be approached by any other means except religious. This conclusion is challenged by closer readings of Otto s writings on naturalism and religion where he, despite of being at times critical of some versions of naturalism, expresses his thorough commitment to naturalistic explanations. Otto s views are presented as compatible with recent cognitive-scientific theories of religion and as a constructive contribution to the scientific study of religion. Otto s theological position, because it is based on his naturalism, is a possible methodological framework for further studies in religion and science in general and cognitive science of religion in particular.