The German Ideology
What distinguished Marx from Feuerbach was his view of Feuerbach's humanism as excessively abstract, and so no less ahistorical and idealist than what it purported to replace, namely the reified notion of God found in institutional Christianity that legitimized the repressive power of the Prussian state. Instead, Marx aspired to give ontological priority to what he called the "real life process" of real human beings, as he and Engels said in "The German Ideology" (1846):