Just when you think we've managed to drag most of humanity out of the darkness and cloying fear of superstition and unjustified beliefs, someone stabs a baby.
Told by a witchdoctor that sacrificing their baby girl would make them rich, this Pakistani couple did what any good believer in the supernatural would do. They killed their baby.
I can't think of any clearer example of the dangers of believing in something without evidence. When people ask what's the harm when people have a personal, private belief in something, you can point at this dead baby girl and say "That's the harm."
These people believed in magic. This meant that when the witchdoctor, a trusted authority figure in their belief system, told them that killing their baby would make them rich, it made sense.
If they hadn't believed in magic, or if they hadn't been monstrous enough to believe that being rich was worth more than the life of their baby girl, they wouldn't have performed the sacrifice.
There is no such thing as a belief in a vacuum. When you believe in something, it shapes the way you live your life and how you deal with others. Unfortunately for this little girl, her parents believed she needed to die.