40 What then must be done, what remedies must be employed to defend Christ and Christian civilization from this pernicious enemy? As a father in the midst of his family, We should like to speak quite intimately of those duties which the great struggle of our day imposes on all the children of the Church; and We would address Our paternal admonition even to those sons who have strayed far from her.
Source: Divini Redemptoris (Vatican.va)