You are misinterpreting the Bible on slavery, murder for minor indiscretions, and etc. What is a minor discretion that gets the death penalty. Further, please allow me to explain how the death penalty handed out. Two, not one, but two knowledgeable people have to actually see the discretion as it happens. Not only that, but they have to worn the person of the act he is about to commit. What does that mean? It means they have to make sure the person not only understands what he is doing is wrong, but why it's wrong, and what the punishment is. Now, how often does it happen that witnesses can do that? The death penalty is therefore nearly impossible to hand out.
As for living a life of torture, what's the point of living a life of poor health? Not all medical issues are treatable, believe me, I know from personal experience. What is the point in my painful existence? I'll tell what I believe. I believe this is what I need to purify my soul so that it can move on the world to come (yes, I do believe in reincarnation, and that we keep coming back until we get it right). I have physical problems, other people have internal problems. For example, former president Bill Clinton has a problem being a faithful husband. That is his problem to work on in this world. He could not act on his feelings, which would have saved him the embarrassment of impeachment, or he could act on those feelings, which he did. I do believe it is that simple, and that there is a higher purpose to our personal problems in life.