Imagine you were going to start an organization. One with the intent of being totally immoral and evil. Lets call it Satanism. You'd need some sort of way to weed out those with a conscience. Those who might have limits to their depravity. So you'd have to harm an innocent in a way that offers no benefit to the perpetrator, but causes irreparable damage to the innocent. I can think of no better indoctrination than mutilating the genitals of a baby.