33 Thousands of voices ring into your ears a Gospel which has not been revealed by the Father of Heaven. Thousands of pens are wielded in the service of a Christianity, which is not of Christ. Press and wireless daily force on you productions hostile to the Faith and to the Church, impudently aggressive against whatever you should hold venerable and sacred. Many of you, clinging to your Faith and to your Church, as a result of your affiliation with religious associations guaranteed by the concordat, have often to face the tragic trial of seeing your loyalty to your country misunderstood, suspected, or even denied, and of being hurt in your professional and social life. We are well aware that there is many a humble soldier of Christ in your ranks, who with torn feelings, but a determined heart, accepts his fate, finding his one consolation in the thought of suffering insults for the name of Jesus ( Acts v. 41). Today, as We see you threatened with new dangers and new molestations, We say to you: If any one should preach to you a Gospel other than the one you received on the knees of a pious mother, from the lips of a believing father, or through teaching faithful to God and His Church, "let him be anathema" ( Gal. i. 9). If the State organizes a national youth, and makes this organization obligatory to all, then, without prejudice to rights of religious associations, it is the absolute right of youths as well as of parents to see to it that this organization is purged of all manifestations hostile to the Church and Christianity. These manifestations are even today placing Christian parents in a painful alternative, as they cannot give to the State what they owe to God alone.
Source: Mit Brennender Sorge (Vatican.va)