It is Marxism which emphasises this fact. Marxist theory identifies religion as a major player in the relationship between the bourgeoisie and the proletariat, a relationship based on conflict. This is a relationship based on exploitation and inherent economic conflict. Marx saw religion as part of the capitalist superstructure, and as a tool for subverting dissidence and achieving control. Religion can dull the pain of oppression in a number of ways.
Some religions make a virtue of suffering.
In particular, those who suffer the hardships of poverty with humility and dignity will be rewarded. Therefore, religion makes poverty and hardship more tolerable by offering a reward for suffering and promising justice in the afterlife. Also, religion can offer the hope of supernatural intervention to solve the problems of life. Some groups even wait for the day of redemption when heaven is created on earth. This type of anticipation for a future paradise can make the hardships of the present far more tolerable.