Is Religion the Opium of the People?

There's long antagonism between political revolutionary movements of the modern era and organized Christianity. The French Revolution is for good reasons, regard the Catholic Church as one of their most dangerous institutional opponents. In pre-revolutionary Russia, the Orthodox Church was deeply entangled with the Tsarist regime. And so it's not at all surprising that communist regimes would regard religion in general and Christian churches in particular as some of theirmost dangerous antagonists.