The steps taken by the Church Fathers towards the abolition of the spirit were carried a stage further by Marx and Engels in their comprehensive attempt to abolish the soul. According to the materialistic theory of history spiritual impulses are of no account, the driving forces of history are material forces or economic factors — the struggle for material wellbeing. What appertains to the soul is simply a superstructure on the solid foundation of material processes. It is important to recognize the genuine catholicity of Marx and Engels and to note in these aspirations of the nineteenth century the true consequence of the abolition of the spirit. […] It will not be long before decrees are promulgated in several States declaring that those who take seriously the existence of the soul are not of sound mind, and only those will be regarded of sound mind who recognize the “truth”, namely that thinking, feeling and willing are the necessary by-products of certain physiological processes.
Source: Rudolf Steiner – GA 175 – Building Stones for an Understanding of the Mystery of Golgotha: Lecture 1 – Berlin, 27th March 1917