League of Militant Atheists
The League of Militant Atheists, also known as the League of the Militant Godless, the Society of the Godless, and the Union of the Godless, was an atheist and anti-religious Communist organization in the Soviet Union, founded in 1925 and disbanded sometime between 1941 and 1947. By the beginning of 1941, it had about 3.5 million members and about 96,000 offices across the country. The League aimed at ending religion in all its manifestations and forming an anti-religious scientific mindset among the workers. It was founded by the Jewish Yemelyan Yaroslavsky.
Leftist Wikipedia has a rather positive description of the organization, downplaying the Communist persecutions of religious people and organizations and the destruction of cultural heritage.
When National Socialist Germany invaded in 1941, churches were re-opened under the German occupation, while believers flocked to them in the millions. In order to gain support for the war effort (both domestic and foreign from the Allies), Stalin ended the antireligious persecution. All LMG periodicals ceased to publish by September 1941. Its official disbandment date is unknown, but traced somewhere between 1941 and 1947.
