Our Daily Bread today referred to one symptom of leprosy that causes more damage than the virus itself. It seems the bacillus Mycobacterium leprae attacks the pain receptors and nerves that transmit pain signals to the brain.
I don't know about others, but a pain-free life sounds like Paradise--until I consider my instant reaction to pain-causing injuries. Neither the heat of fire nor the raking friction of abrasion cause us to defend ourselves from injury. Instead, it is the pain of such circumstances that motivates us to take evasive action. Without the pain-warning, we would aggravate injuries by ignoring them.
Conscience provides the same function for our spiritual and social behavior. It warns us when we're considering an action or thought that crosses our moral code. Without it, no action would be too depraved, no injury to another would be too grievous. Instead of a Hitler or a Bundy being an aberration, their crimes would be the norm and safety would be an unknown concept.
Nothing as concrete as a virus, however, causes the conscience-numbing that I call spiritual leprosy. Conscience is a respectful being, who will never assert her advice where it's not wanted. All we must do to keep it from bothering us is to ignore it. Before long it becomes jaded and ceases functioning, allowing us to pass into reprobation. To those whose consciences are numbed, reprobation is preferable to having moral rules cramp their style.
Why do people do bad things? Because they want to, and they've managed to silence their consciences. Moral reprobation--what I call spiritual leprosy--is terminal, but unlike physical leprosy, the death it brings is final and eternal.