Instead of studying the ideas of God and religion, Otto undertook to analyze the modalities of the religious experience. Gifted with great psychological subtlety, and thoroughly prepared by his twofold training as theologian and historian of religions, he succeeded in determining the content and specific characteristics of religious experience.
Eliade identifies Otto's methodological innovation — the phenomenological analysis of religious affect rather than theological doctrine — as the point of departure for the modern science of religion.
, The Sacred and the Profane: The Nature of Religion, 1957thesis