This chapter synthesizes the book’s key findings on the phenomenology and neural correlates of psychedelic experiences alongside the historical use of psychedelics in religious practices. It explores the subjective effects of psychedelics, including mystical experiences, encounters with God or other supernatural entities, death experiences, and shifts in metaphysical beliefs. It also investigates the underlying pharmacological and neural mechanisms, emphasizing the leading models of psychedelic action. The chapter further examines historical evidence of psychedelic use in religious practices across cultures. Acknowledging limitations in current research, it advocates for rigorous scientific inquiry employing advanced analytical methods such as archaeogenetic, archaeochemical, and archaeobotanical techniques, along with an interdisciplinary approach that brings together archaeologists, anthropologists, historians, neuroscientists, and other scholars. This approach will provide a more comprehensive understanding of the historical and cultural significance of psychedelic use in religious practices.