An essential feature of religious experience across many cultures is the intuitive feeling of God's presence. More than any rituals or doctrines, it is this experience that anchors religious faith, yet it has been largely ignored in the scientific literature on religion. Starting with a vivid narrative account of the life-threatening hike that triggered his own mystical experience, biologist John Wathey takes the reader on a scientific journey to find the sources of religious feeling and the illusion of God's presence.