5 It is true, indeed, that wicked men were never wanting, nor men who denied the existence of God; but these last were very few in number, and, being alone and singular, they either feared to express their evil mind openly, or thought it inopportune to do so. The Psalmist, inspired by the Divine Spirit, seems to hint this in those words: "The fool hath said in his heart: There is no God" ( Ps . xiii. 1, lii. 1); as though he showed us such an impious man, as one solitary in a multitude, denying that God his Maker exists, but shutting up this sin in his innermost mind. But in this age of ours, this most pernicious error is now propagated far and wide amid the multitude, it is insinuated even in the popular schools, and shows itself openly in the theaters; and in order that it may be spread abroad as far as possible, its advocates seek aid from the latest inventions, from what are called cinematographic scenes, from gramophonic and radiophonic concerts and discourses; and possessed of printing offices of their own, they print books in all languages, and, taking a triumphant course, they publicly display the monuments and documents of their impiety. Nor is this enough; for dispersed among political, economical and military parties, and closely associated with them, through their heralds, by means of committees, by pictures and leaflets, and all other possible means, they labor diligently in the evil work of spreading their opinions among all classes and societies, and in the public ways; and to carry this further, supported by the authority and work of their universities, they succeed at last by forceful industry in binding fast those who have incautiously allowed themselves to be aggregated to their body. When We consider all this careful labor devoted to the advantage of an unlawful cause, that most sad complaint of Christ our Lord spontaneously rises in our mind and on our lips: "The children of this world are wiser in their generation than the children of light" ( Luke xvi. 8).
Source: Caritate Christi Compulsi (Vatican.va)