Somehting that ruins the world. It's responsible for all major wars and has caused suffering and death of millions of people. This world would be a much better place with out religion. Religion has caused more bad then good. Religious people do good things for selfish reason (ie fear of god or reward from god). People only follow religion cause their too weak-minded to accept that we don't know what happens after we die, it comforts them to think there is an afterlife. But the truth is we don't know and can't know untill we die. This world could progress in science and intelligence if religion was abolished. People would appreciate life more and there'd be alot less violence.
From everything I've seen religion has harmed more than helped.