Columbia subject headings:
Engels, Friedrich, 1820-1895--Religion.
Marx, Karl, 1818-1883--Religion.
Socialism and Christianity--Catholic Church--Germany--History--19th century.
Socialism and Christianity--Germany--History--19th century.
Socialism and religion.
Harvard subject headings:
Engels, Friedrich, 1820-1895--Religion.
Marx, Karl, 1818-1883--Religion.
Socialism and Christianity--Catholic Church--Germany--History--19th century.
Socialism and Christianity--Germany--History--19th century.
Socialism and religion.
Princeton subject headings:
Communism and Christianity--History.
Socialism and religion--History.