Religions, schools of ethics, philosophy, metaphysics, art, political and juridical institutions are all to be explained in the last analysis by the economic and telluric environments, present and past. This ruthless materialism crushes belief in God, in the Soul, in immortality. It leaves no room for any shred of dualism in thought. It is true that the German Social Democracy included in the famous Erfurt Programme (adopted in 1891--the first clearly Marxian socialist platform ever promulgated) a demand for a "Declaration that religion is a private matter. Abolition of all expenditure from public funds upon ecclesiastical and religious objects. Ecclesiastical and religious bodies are to be regarded as private associations, which order their affairs independently." It will be seen that this is nothing more than a demand that the State withdraw its sanction of religion as France has recently done in the Clemenceau law. But Ferri does nothing but draw the necessary conclusions from socialist premises when he writes: "God, as Laplace has said, is an hypothesis of which exact science has no need; he is, according to Herzen, at the most an X, which represents not the _unknowable_--as Spencer and Dubois Raymond contend--but all that which humanity does not yet know. Therefore, it is a variable X which decreases in direct ratio to the progress of the discoveries of science. "It is for this reason that science and religion are in inverse ratio to each other; the one diminishes and grows weaker in the same proportion that the other increases and grows stronger in its struggle against the unknown."[14] Joseph Dietzgen has thus stated what may be called the law of the atrophy of religion: "The more the idea of God recedes into the past the more palpable it is; in olden times man knew everything about his God; the more modern the form of religion has become, the more confused and hazy are our religious ideas. The truth is that the historic development of religion tends to its gradual dissolution."[15] The characteristic attitude of the socialist materialist toward Christianity appears very clearly in the following excerpt from Professor Ferri's "Socialism and Modern Science": "It is true that Marxian Socialism, since the Congress held at Erfurt (1891), has rightly declared that religious beliefs are private affairs[16] and that, therefore, the Socialist party combats religious intolerance under all its forms.... But this breadth of superiority of view is, at bottom, only a consequence of the confidence in final victory.