From Wikipedia:
The story centers on the invention of a reactor that can annihilate matter to produce cheap and abundant energy (cf. mass–energy equivalence). Unfortunately, it produces something else as a by-product, the absolute. The absolute is a spiritual essence that according to some religious philosophies allegedly permeates all matter (see also monism). It is associated with human religious experience, as the unsuspecting humanity is to find out all too soon in the story. The widespread adoption of the reactors cause an enormous outpouring of pure absolute into the world. This leads to an outburst of religious and nationalist fervor, causing the greatest, most global war in history.