Most religious beliefs aren’t matters of life and death. You might waste your time praying to a god. You might have to eat a tasteless communion wafer sometimes. Even accepting Creationism just prevents you from understanding the beauty of science. But that’s usually the worst of it.
Jehovah’s Witnesses, on the other hand, hold a belief that makes no sense and has led to multiple deaths: They refuse to undergo blood transfusions even if it means saving their own lives, a belief that stems from irresponsible interpretations of the Bible. It’s especially disgusting when the children of JW parents are the ones who are suffering and their parents would rather see their kids die than have the life-saving procedure done.