I think part of it is down to the basic theology of Evangelical Christianity, which is sadistic. Evangelical Christians are taught that almost all humans ever born (or who will be born) are tortured in hell (burned without being able to die) for eternity, but that a select few (them, Evangelical Christians) have been saved from that fate because God tortured his son to death.

It's not much of a leap from that theological horror show to believing that torturing living humans is acceptable if it will save them from their "sin."

Add to that that many Evangelical Christians deny science and believe in miraculous interventions in this world, and you can begin to imagine how a torturing monster like Cindy can exist.