Marx and Engels' work covers a wide range of topics and presents a complex analysis of history and society in terms of class relations. Followers of Marx and Engels have drawn on this work to propose a political and economic philosophy dubbed Marxism.
Nevertheless, there have been numerous debates among Marxists over how to interpret Marx's writings and how to apply his concepts to current events and conditions (and it is important to distinguish between "Marxism" and "what Marx believed."
Essentially, people use the word "Marxist" to describe those who rely on Marx's conceptual language (e.g. means of production, class, commodity) to understand capitalist and other societies, or to describe those who believe that a workers' revolution is the only means to a communist society.
Marxism has influenced Christian thought, too, especially liberation theology, which argues in favor of God's special concern for, or bias towards, the poor and advocates that when the poor become conscious of their exploitation, they will then be empowered to demand and achieve their rights. Liberation theologians do not necessarily support violence as part of this process, although many have.
Six years after Marx's death, Engels and others founded the "Second International" as a base for continued political activism. This organization collapsed in 1914, in part because some members turned to Edward Bernstein's "evolutionary" socialism, and in part because of divisions precipitated by World War I.
Further Reading : Marx, Karl - http://www.newworldencyclopedia.org/entry/Karl_Marx