Pius XI states that “bolshevistic and atheistic Communism” threatens “Christian civilization” everywhere and promises a new barbarism worse than that of Jesus’ time. It aims at “upsetting the social order” and undermining Christianity’s foundations. He states that the Church cannot remain silent and must defend truth and justice.Pius XI had already condemned communism in five encyclicals beginning in 1924 when he wrote the 1937 encyclical. In this encyclical, he relates how as early as 1846, Pius IX had condemned communism, and Leo XIII labeled it a “fatal plague.” However, from its center in Moscow, communism continues to “struggle against Christian civilization.” Bishops also have spoken out against communism, but the pope says that “clever agitators” and their “subversive ideas” only grow in influence. In the encyclical, he states that he will present communism’s most corrosive ideas, uncover its method of action, and refute its claims with the truth of the Church.