When they saw the universal desire for peace, the representatives of communism pretended to be the most ardent supporters and promoters of the movement for worldwide peace. At the same time, however, they incite a relentless class struggle, during which rivers of blood flow, and when they feel they do not have an internal guarantee of peace, they build enormous armed forces. Similarly, under names that do not even remotely resemble communism, they establish various associations and periodicals that serve exclusively to penetrate their ideas into environments that would otherwise be very difficult to access.
Take care, venerable brothers, that the faithful are not deceived! Communism is inherently corrupt, and therefore, it cannot be admitted that anyone who wishes to strive for the salvation of Christian civilization could collaborate with it in any field.
(Pius XI, encyclical Divini Redemptoris; no. 1255-6; March 19, 1937)
