A Systems Theory of ReligionA Systems Theory of Religion, still unfinished at Niklas Luhmann's death in 1998, was first published in German two years later thanks to the editorial work of Andr Kieserling. One of Luhmann's most important projects, it exemplifies his later work while redefining the subject matter of the sociology of religion. Religion, for Luhmann, is one of the many functionally differentiated social systems that make up modern society. All such subsystems