"Religion is the opium of the people."
"Man makes religion; religion does not make man."
"The abolition of religion as the illusory happiness of the people is the demand for their real happiness."
"Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions."
"The criticism of religion is the beginning of all criticism."
"Religious suffering is at the same time an expression of real suffering and a protest against real suffering."
"The foundation of irreligious criticism is: man makes religion, religion does not make man."