which in Marx's opinion was their capitalist economic system. In this perspective, Marx saw religion as escapism. Marx also viewed the Christian doctrine of original sin as being deeply anti-social in character. Original sin, he argued, convinces people that the source of their misery lies in the inherent and unchangeable "sinfulness" of humanity rather than in the forms of social organization and institutions, which Marx argued can be changed through the application of collective social planning. Viruses of the mind In his 1976 book The Selfish Gene, Richard Dawkins coined the term memes to describe informational units that can be transmitted culturally, analogous to genes. He later used this concept in the essay "Viruses of the Mind" to explain the persistence of religious ideas in human culture. Response to the viruses of the mind criticism Religious and non-religious people are both critical of Dawkins' meme theory. Some have criticized the idea that "God" and "Faith" are viruses of the mind, suggesting that it is far removed from evidence and data" that it is unreasonable to extract certain behaviours solely through religious memes. Alister McGrath has responded by arguing that "memes have no place in serious scientific reflection", or that religious ideas function the way Dawkins claims. Mental illness or delusion Sam Harris compares religion to a mental illness, saying that it "allows otherwise normal human beings to reap the fruits of madness and consider them holy". According to a retrospective study of Abraham, Moses, Jesus Christ, and the Apostle Paul, they may have had psychotic disorders that contributed inspirations for their revelations. They conclude that people with such disorders have had a monumental influence on civilization. Psychological studies into the phenomenon of mysticism link disturbing aspects of certain mystics' experiences to childhood abuse. Clifford A. Pickover found evidence which suggests that temporal lobe epilepsy may be linked to a variety of so-called spiritual or "other worldly" experiences, such as spiritual possessions, which occur as the result of altered electrical activity in the brain. Carl Sagan, in his last book The Demon-Haunted World: Science as a Candle in the Dark, presented his belief that the miraculous sightings of religious figures and modern sightings of UFOs were all caused by the same mental disorder. Vilayanur S. Ramachandran suggests "It's possible that many great religious leaders had temporal lobe seizures and this predisposes them to having visions, having mystical experiences". Michael Persinger artificially