"It is of the very essence of social justice to demand from each individual all that is necessary for the common good."
....."In unforgiving terms, Pius XI decries communism as inherently atheistic, intrinsically perverse, and wholly at odds with Christian teaching. The encyclical moreover charges that communism robs human persons of their dignity and strips them of their liberty. The scathing language is tempered only by the qualifier that the Roman Catholic Church wishes warm affection for the peoples of the Soviet Union who remain trapped under so terrible a regime. Pius XI also expressed concern over the growing influence of communism in Spain and Mexico at the time".
(Georgetown University - Berkeley Centre for Religion, Peace and World Affairs)