In spite of his influence on the subject, Karl Marx never studied religion in any detail. His ideas were mostly derived from the writings of several early 19th century theologists and philosophers.One of these was Ludwig Feuerbach who wrote The Essence of Christianity. According to Feuerbach, religion consists of ideas and values produced by human beings in the course of their cultural development but mistakenly projected on to divine forces or gods.Feuerbach uses the term alienation to refer to the establishment of Gods or divine forces as distinct from human beings.
Marx accepts the view that religion represents human self-alienation. He declared in a famous phrase that religion has been the opium of the people. Religion defers happiness and rewards to the after life, teaching the resigned acceptance of existing conditions in this life. Attention is thus diverted from inequalities and injustices in this world by the promise of what is to come in the next. Religion has a strong ideological element, religious beliefs and values often provide justifications for inequalities of wealth and power. In Marx's view religion in its traditional form will and should disappear.