The article deals with understanding of religion within the theory of "autopoietic systems" of Niklas Luhmann. Religion acts as a continuous, renewable "control over the border with the unknown", as "a knowledge of the mysterious". Three typological and historical forms of religion are idenitified in Luhmann’s theory: the magical-mythological tradition of early societies; a dichotomous differentiation of "Great Tradition / little tradition" in the period of great imperial civilizations; and current forms of religiosity in modern and postmodern "differentiated society".