What is it with the criminal justice system in the U.S. and sadism?

Often, in the U.S. citizens feel that serving time isn't enough. They feel prison should be a cruel place where prisoners get d and beaten (mostly by other prisoners and sometimes by guards) and all sorts of things. They feel the conditions in there should be as harsh as possible. U.S. prisons are extremely violent and stressful places and they are specifically designed to be that way. And then there are the methods in which prisoners in the U.S. are executed. There is the lethal injection (which isn't administered by doctors because they refuse to participate in such a thing) where the prisoner looks like he is unconscious but is really experiencing hellish convulsions for minutes before he dies. And then there is the electric chair. Geez. Talk about sadistic. Why not just go with a firing squad already and get it over with. Why all of the theatrics? In other industrialized countries, the sentences aren't as harsh and the conditions in the prisons aren't as rough. People in Western Europe feel that serving time (without all of the sadism) is enough of a punishment. But here it's a different story. Do you think it is because of the Christian mindset that is so popular in the U.S.? Does religion have anything to do with the attitudes that citizens have towards crime and punishment?