The article examines the theoretical development of Czech sociology of religion during the period of communist rule, which widely affected the social sciences in general and research on religion in particular. The author divides the period into three different stages. First, from the very end of the 1940s to the beginning of the 1960s sociology as a whole was abolished as a 'bourgeois pseudo-science', and any discourse on religion was possible only in purely negativistic, anti-religious terms. However, some scholars (most notably A. Kolman, E. Kadlecová and I. Sviták) established less ideological attitudes and called for deeper sociological analyses of religion at the end of the 1950s and the start of the 1960s. Their 'revisionism' eventually won out in the 1960s, in the second stage, when Czech sociology of religion achieved international acceptance and Kadlecová became (for a short time) the author of the state's new religious policy. Although these scholars (V. Gardavský and M. Machovec) accepted a wider definition of religiosity and debated with Christian scholars, they remained Marxists. They were convinced religion is doomed to extinction. The last stage began after the violent termination of the Prague Spring in 1968 and lasted throughout the era of the so-called normalisation in the 1970-80s. Progressive scholars were removed from their posts. The official sociology of religion changed its name to 'scientific atheism', but the outcomes of its work were far from any standard of excellence, both in the theoretical and empirical fields. Research from the era of official neo-Stalinism was very poor in quality, but during that time very important unofficial scientific contributions did emerge, written by banned sociologists (E. Kadlecová, J. Siklová), social theologians (B. Komárková), and Czechs in exile. Unfortunately, since 1989 the reception of these works has been narrow. With the abolition of official Marxist scientific atheism there is an opportunity for the spread of truly modern sociological approaches to religion - if only there were enough students.