Dialectical materialism is an idea put forth by Karl Marx and Friedrich Engels, the authors of The Communist Manifesto. It states that all economic and political change comes from the conflict between two diametrically opposed economic and social classes (the "thesis" and "antithesis"). The resolution to this conflict leads to a new consensus, distinct from the original ideas (the "synthesis") It is derived from the theories of Hegel.
Like the founder of a new religion, Marx believed he had unlocked the secrets of the universe in the form of "scientific laws." Among these laws were the following:
1) Atheism: the denial of the existence of God. Marx referred to religion as "the opium of the masses." According to atheist humanism, the universe came into being by accident. Marx's system requires this presupposition because it means that standards of value and morality are changeable rather than fixed, relative rather than absolute. As a consequence, men--specifically the ruling classes--are free to determine their own rules.
2) Materialism: Marx believed that "there is nothing in the world apart from matter in motion." Thus men's thoughts and emotions, seen as by-products of matter in motion, may properly be scientifically controlled by those who seek to further human "progress". John Dewey's progressive education system fits this model.
3) Class Struggle: The dialectical struggle between a new working class (the "proletariat") and the supposed old capitalist ruling class (the "bourgeoisie") results in the creation of a new kind of human being - a new man - and in turn produces the inevitable triumph of the new class, which then establishes its dominion over the whole earth. The victory of the proletariat is supposed to lead to a "classless society". This is the Marxist equivalent of salvation. In the absence of absolute values, it becomes an end that justifies almost any means.