Undeniably, those who willfully shut out God from their hearts and try to dodge religious questions are not following the dictates of their consciences, and hence are not free of blame; yet believers themselves frequently bear some responsibility for this situation. For, taken as a whole, atheism is not a spontaneous development but stems from a variety of causes, including a critical reaction against religious beliefs, and in some places against the Christian religion in particular. Hence believers can have more than a little to do with the birth of atheism. To the extent that they neglect their own training in the faith, or teach erroneous doctrine, or are deficient in their religious, moral or social life, they must be said to conceal rather than reveal the authentic face of God and religion.
Modern atheism often takes on a systematic expression which, in addition to other causes, stretches the desire for human independence to such a point that it poses difficulties against any kind of dependence on God. Those who profess atheism of this sort maintain that it gives man freedom to be an end unto himself, the sole artisan and creator of his own history. They claim that this freedom cannot be reconciled with the affirmation of a Lord Who is author and purpose of all things, or at least that this freedom makes such an affirmation altogether superfluous. Favouring this doctrine can be the sense of power which modern technical progress generates in man. Not to be overlooked among the forms of modern atheism is that which anticipates the liberation of man especially through his economic and social emancipation. This form argues that by its nature religion thwarts this liberation by arousing man's hope for a deceptive future life, thereby diverting him from the constructing of the earthly city. Consequently when the proponents of this doctrine gain governmental power they vigorously fight against religion, and promote atheism by using, especially in the education of youth, those means of pressure which public power has at its disposal. (Second Vatican Council. Gaudium et Spes, 1965).
The Jews and early Christians were accused of atheism by the Romans because they refused to recognize the Roman gods and the Emperor as divinities. Orthodox Christians used the accusation against various heretics, notably those who acknowledged God but denied the Trinity.
2. Atheism, both by etymology and by usage, is essentially a negative conception presupposing the existence of theism. It is therefore not the replacement of a specific understanding of God with another specific understanding of God. It can arise from the believe that matter and physical force constitute the ultimate reality of the universe, and that, through the aggregation of the elements of matter in various organic forms, life and the infinitely varied forms of consciousness has emerged, [ie] materialism. Sensationalism can also be a source of atheism; [ie] the belief that all ideas are derived from sensations or from reflection on sensations.
3. Still, many of our contemporaries recognize in no way this intimate and vital link with God, or else they explicitly reject it. Thus atheism must be accounted among the most serious problems of this age, and must be subjected to closer examination. (Second Vatican Council).
4. 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 theatres; 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 labour 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. And by this line of argument they strive, not without fatal effect, to mix up the struggle for daily food, the desire to possess a smallholding, to have a fair wage, an honourable home and, lastly, those conditions of life that are not unworthy of a man, with their iniquitous war against God. In this wise, this new form of impiety, while it removes all checks from the most powerful lusts of man, most impudently proclaims that there will be no peace and no happiness on earth until the last vestige of religion has been uprooted, and the last of its followers beheaded. (Papal Encyclical, Caritate Christi Compulsi, 3 May 1932).
5. It may be asked, in what way do the Modernists contrive to make the transition from Agnosticism, which is a state of pure nescience, to scientific and historic Atheism, which is a doctrine of positive denial; and consequently, by what legitimate process of reasoning, they proceed from the fact of ignorance as to whether God has in fact intervened in the history of the human race or not, to explain this history, leaving God out altogether, as if He really had not intervened. Let him answer who can. Yet it is a fixed and established principle among them that both science and history must be atheistic: and within their boundaries there is room for nothing but phenomena; God and all that is divine are utterly excluded. We shall soon see clearly what, as a consequence of this most absurd teaching, must be held touching the most sacred Person of Christ, and the mysteries of His life and death, and of His Resurrection and Ascension into Heaven. (Papal Writings, Pascendi Dominici Gregis: On the Doctrine of the Modernists, 8 September 1907).