Edward Drinker Cope (1840–1897) has been lauded as America's first great evolutionary theoretician (Gould, 1977: 85), yet his religious life remains enigmatic. This paper explores Cope's Quaker background to correct popular misconceptions as to why he used singular second-person pronouns (thee, thy, thine) and numbers for days and months in his private speech, why he used guns in hunting while refusing to use military weapons or wear military uniforms, and his treatment of Native Americans as equals. It also examines why Cope resigned from the Society of Friends, his Quaker wedding to Anne Pim (1841–1933) and their later separation, and his subsequent philosophical journey.