From Slate Star Codex:
This project seeks to explore the viability of spiritual or religious experiences as empirical evidence for a component of reality that transcends or is radically different from our ordinary experience. The question at hand is not the existence of God or higher powers, nor the failures, successes, or benefits of religion, but rather the role of spiritual experience in the human understanding of the nature of reality. We formulated the topic in controversy this way:
The empirical study of the content and nature of people’s personal spiritual experiences justifies taking them seriously as evidence of an important component of human life deserving of individual and collective exploration.
Our fellow human beings have always had unusual experiences that they found special and meaningful, but often struggled to interpret or place in the context of their ordinary lives. These experiences and their interpretation have aroused intense controversy, both because people have deployed them as support for their views on contested issues about the nature of reality, and because they may arise in settings where one could easily question whether the brain’s altered perceptions and understandings are enhanced or impaired. Another source of debate is how radically different individuals’ experiences—and their personal interpretations of the origins and meanings of those experiences—can be. Finally, spiritual experiences are often reported through a cultural lens that leads to questions about how accurately and objectively people could perceive and describe the unusual things that they perceived.