While the Soviet state perceived all religion to be the opium for the people, in reality it promoted a differentiated policy towards religious groups. While Eastern Orthodox Christians were also persecuted, in comparison with other denominations they were generally treated more favourably. Due to several factors outlined here, Jehovah’s Witnesses were amongst the most repressed and were subject to mass deportations to the Gulag. This chapter, based on newly available archival material, highlights another aspect of the repression of the Jehovah’s Witnesses, namely the heavy infiltration of their networks in Soviet Moldavia by state security organs from 1944 to late 1950s. This strategy in some ways resembled the methods used by Soviet security organs against the armed anti-Soviet insurgents in Western Ukraine and the Baltics, especially in Lithuania. Agent infiltration of the internal enemy became one of the main strategies of the state security organs or political police after the Second World War. This chapter argues that ideology played an important role in the repression of so-called anti-Soviet elements, including religious groups, but that context and the agency of infiltrated groups also needs to be considered when seeking to understand these actions. I also outline how Soviet concepts and practices of repression were predated by other political regimes including, to a certain extent, those of Tsarist Russia.