In the New Testament, Jesus condemns the "eye for an eye" principle, saying:
"You have heard that it was said, ‘Eye for eye, and tooth for tooth.’ But I tell you, do not resist an evil person. If anyone slaps you on the right cheek, turn to them the other cheek also. And if anyone wants to sue you and take your shirt, hand over your coat as well. If anyone forces you to go one mile, go with them two miles. Give to the one who asks you, and do not turn away from the one who wants to borrow from you" (Matthew 5:38-48).
Yet I find it ironic that many Christians would argue that God would send people to eternal torment for not having a Christian faith. To me, this view of eternal torment as a punishment for disbelief is far more harsh than "an eye for an eye." For this reason, I personally think it's nonsense, and I actually believe that Jesus didn't ever preach this doctrine. Of course, Jesus talked about hell, but it was always in regards to action (Link).
Sending a person to eternal torment for living a life of skepticism is definitely cruel and unusual punishment to me. It's also far more harsh than the "eye for an eye" principle. Ultimately, I will never accept the notion that a just God would promote "cruel and unusual punishment."