Which is the most wisespread disease? Which meme has affected the mankind in the most fatal way? Yes, it's religious fanatism. Jingoism, regional biases, discriminations based on the language take a seconadary pedestal when it comes to the things which contaminate the humans. Religious fanatism springs from something which looks like hard coded in the DNA of the majority of population. I do not know what it's but Atheists are intolerant of other religions, Hindus are intolerant of Muslims, Muslims are intolerant of Christians and so and so on. What is so dramatic about attachment to your views? There can be Scientific fanaticism as well. Some scientifically minded people would abhor mistakes and in spite of not being able to explain 99% of the things, they prefer sitting with puckered faces instead of wondering about reality.Fanaticism is because of inability to get detached from your views. Most of the people inherit faith from their family of birth. They inherit culture, language, mannerisms and thoughts mostly from their society of birth and in doing so they are so dramatically hard-coded for becoming callous to other view-points that they turn into fanatics. Education in the sense of tabula-raisa feeding of words into the mind, as has been the case with it for most of the last century, does nothing to improve it. We hardly get a chance to look at our views from a view-point which is not ours. We live in fear and die in it. We need a feeling of belonging and therefore we follow rituals, mannerisms and languages spoken by our neighbors, lest they ostracize us. It's very difficult to walk a lonely road. To be without a faith, to be without a God, to be without a nationality or to be without an opinion of yours. To speak out quickly is important and to have ceratin-well defined faith is even more important. You have to join this group, club, secret-society or the other; well man has always been a social animal. You have to have one 'ism' otherwise you're a schmuck. Tags are invented to be used and if you do not fit into the tags, either you invent your own vocabulary and describe your views relentlessly to a mad mob which had long before shut its ears dumb dead, or, be ready to get stoned, to be ostracized.
Since it's written in their book it's The Truth. Since there are myriads upon myriads of people who have spent their lives memorizing what is written in their books, it's The Truth. Since a few people came in history and said " What I am saying is Truth and don't believe anyone else," it's Truth. Fanaticism is such a peculiar meme that it contains well hard-coded traits inside it which turn it off for any intereference from out side forever. People go berserk if you criticise their favorite cricketers or actors. They become mad and burn your effigies if you question their values and their religious fanaticism. It seems, as if people need something to oppose, something to go against; something to burn effigies for, something to get violent for, something to create jokes about; otherwise, the plain ordinary living becomes an existential nightmare, where, they don't gain enough of attention or feel deprived of nourishment which this great feeling of belonging gives to them.