Like the year 1830, 1848 was another one of revolutions across Europe. Early in that year, Karl Marx (1818-83) and Friedrich Engels (1820-95) published The Communist Manifesto (1848). It opened with the words, “A spectre is haunting Europe—the spectre of communism. All the powers of old Europe have entered into a holy alliance to exorcise this spectre.”
Earlier, Marx wrote these words about religion (in Critique of Hegel’s Philosophy of Right, 1844):
Religion suffering is, at one and the same time, the expression of real suffering and a protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people.
The abolition of religion as the illusory happiness of the people is the demand for their real happiness. To call on them to give up their illusions about their condition is to call on them to give up a condition that requires illusions. The criticism of religion is, therefore, in embryo, the criticism of that vale of tears of which religion is the halo.