Infidel. Atheist. Rationalist. Agnostic. Occultist Aleister Crowley, soldier J. F. C. Fuller, and poet Victor Neuburg embraced these labels as active contributors and participants in the British secularist movement at the dawn of the twentieth century. Rebelling against Victorian religious and social strictures, they dreamed of a world guided by scientific evidence instead of superstition. Friendship in Doubt examines how the Agnostic movement-from Saladin's Agnostic Journal and G. W. Foote's Freethinker, to the Rationalist Press Association and its Literary Guide--inspired and introduced Crowley, Fuller, and Neuburg to each other as foundational figures in the new religious movement of Thelema. Agnosticism would inform not only Thelema, but also Crowley's publishing company S.P.R.T.; A?A?, a successor to the fragmented Hermetic Order of the Golden Dawn; the Equinox journal; and the concept of "magick" as Scientific Illuminism. This volume also collects for the first time the contributions of all three to the Agnostic literature. This scarce and largely unknown material provides insight into the thinking of Crowley, Fuller and Neuburg at the start of their careers, and an understanding of their subsequent trajectories after they parted ways. As such, it provides unique insights into the role of Agnosticism in the formative years of an emerging occult movement which would go on to exert an immense influence on Western esotericism in the twentieth and twenty-first centuries.