Abstract: The Soviet State the constitution of which recognized the freedom of religion at the same time set as the goal of the legal policy elimination of religion. Analysis of legislation, the archive documents and field studies allowed considering the process of interaction of these mutually exclusive phenomena. With the use of the formal-juridical and historical-legal approaches the peculiar features of the legislation were identified, the methods and results of implementation thereof with respect to the Muslims of the post-war Tatarstan were specified. During this period, the methods of achievement of the goal set were: narrow view of the legislation consisting primarily of the obliging and prohibitive norms; refusal to register the communities of believers under a vein pretext; fighting against the religious practice of the Muslims without registration; pressure of taxation; use of the administrative obstacles for registered communities, etc., many Muslims had to cross over to quasi-legal and illegal pursuit of the religious practice. The Tatar history has already had such an experience; however, during the Soviet period fighting against Islam was more successful. The core values of Islam Zakat, Hajj have disappeared. The others were transformed and started losing their sense and socio-cultural significance. The major cause of weakening of religiosity seems to be the competitiveness of the Soviet ideology in the conditions of the overall poverty during this period.