By Trey Brock, Church Militant - Karl Marx and Friedrich Engels laid the groundwork for Marxism in their 1848 Communist Manifesto. Their manifesto teaches, "The Communists everywhere support every revolutionary movement against the existing social and political order of things."... It further declares "their ends can be attained only by the forcible overthrow of all existing social conditions."... As Marxism has spread its errors all over the world, the Catholic Church remains its biggest threat.