For believers, fear of atheists is fueled by a fear of death

...at an unconscious level, it seems that atheists threatens our beliefs about the nature of existence itself. They serve as a constant reminder of death by denying the presence of a supernatural power who regulates human affairs and monitors the gateway to immortality...
http://www.rawstory.com/2015/06/for-believers-fear-of-atheists-is-fueled-by-a-fear-of-death/