I made a view explorations through the book The Problem of Sociology, written by David Lee and Howard Newby, where the writers deal mostly with the notion 'alienation' on Karl Marx. My second search was in Encyclopedia Brittanica 2009 Student edition, where it states that the most famous use of the term alienation was by Marx, who spoke of alienated labour under capitalism. This is definitely true but, it's also very useful to know that Marx was highly inspired by the writings of preceding people like Adam Smith, David Ricardo, Hegel. A passage from my Sociology textbook says: He(Karl Marx) accepted Feuerbach's assertion that religion was a social creation, bet he suggested that people create religion to deal with the real misery which confronts them.