Religion has taught people that they can own slaves and beat them to death. It has taught that they can kill people for their beliefs and torture them. It tells people that its morality is perfect and from god. So the people who believe it dont want to change their moralities as times change not that these things were appropriate in their time. Religion has caused people to hate others for victimless acts while people who victimize others are praised for it. It causes evil to be considered righteousness and righteousness to be considered evil. Gay is evil murder is god etc. but religion has consistently opposed every moral progress like the mitigation of slavery or every step towards the better treatment of colored races, the diminution of war, every improvement in humane feeling, every improvement in criminal law. The more intense has been the religion of any period and the more profound has been the dogmatic belief, the greater has been the cruelty and the worse has been the state of affairs.
Religion was first created as a way to bring rules to humans (because bashing each other over the head with a rock wasn't good for evolution) However the main idea behind religion is as primitive as when it was made.
You either follow my way because its the right way or you will burn in hell also I might just kill you.
Scaring humans into submission is the name of the game and the powerful like to play it, everyone is afraid of the unknown and whats more unknown than death? Scared people look for answers to soothe their fears, scared people also like to disbelief anything that tries to re awaken those fears. Which is why religions tend to go a bit extreme when you try to disprove God i.e. Public hangings, crucifixion, genocide etc.
So what happens when theres more than one religion? Well its too late because you were told that if you worship another god you will go to hell and burn forever but not just you, no, you got your whole family to worship this god so that means everyone you love could be sent to hell. The very fear that got you to worship in the first place. So like any logical person you have to extinguish that fear like you have been for centuries.
Religion breeds war and only war.
Religion is a peaceful thing gone wrong.
While I respect freedom of religion, I think too many people use religion as justification for why they want to do something. Why is there a genocide in the Middle East? Because the Israelis claim God promised them the Holy Land, so they need to wipe out the Palestinian population already living there. What was the main justification for slavery back pre-Civil War? "It was God's intention for blacks to be inferior to whites." Plus there's the whole Shia/Sunni debacle that's killed thousands upon thousands of people.
There have also been so many wars fought and so much conflict over religion. There was the Catholics vs. The Protestants (especially the Thirty Years' War, which involved the Holy Roman Empire), several civil wars including ones in Lebanon and ones in India, the Holocaust during WWII, extremist terrorist organizations that kill tons of people, the hate between the Pakistani Muslims and the Indian Hindus, etc....The list goes on.
Why is there so much violence as a product of religion? After all, religion does promote peace. Well, the real problem is, each religion claims that they are the one and only truth. When people have the security that they think they know everything, and that security is then challenged, it's not a pretty thing. If you need to be reminded, open a history textbook.
Organized religion, historically and currently drives some people to commit atrocities (e.G. The Crusades, Inquisition, murder of abortion doctors, ISIS, etc.) and are justified by perpetrators claiming, "It's God's will". Evangelical and fundamentalist churches are very self-righteous, controlling and suppress individuality. Any relationship with a higher power should be personal.
Religion teaches people not to examine evidence and rely on 'faith'. As Richard Dawkins has stated it allows people to be "satisfied with not understanding the world". People can hold a number of damaging views (e.G. Homophobic beliefs), and justify these belief using the Bible and religion. Religion was created as a mean of control and it looks as if it's still working.
Religion tried to regulate and improve human behavior . If religion was the cause of anarchy , decadence , then how do explain Stalin and other dictators who had nothing to do with religion .
The moral standard of today is based on religion . If humans are just animals and survival is for the fittest , then where does moral progress and ethics come from ? Moral ethics never came from Kings / Politicians , it came from the Preachers , the Saints etc
True religion which is christianity does more good than harm because it is Gods way of salvation for all mankind through Jesus Christ his son. All other religions are false there is but one God. Anything outside of the true teachings of The Bible and the Catholic Church does more harm than good. The Lord works in mysterious ways that we cannot understand so sometimes certain things may appear to be doing you harm when in fact it is not. You just have to have faith that God knows what he is doing and even if you dont he still does and someday you will be proven wrong.