I'm one of them, although "civilized" or "inhumane" doesn't enter into my thought process. I have no problem with a life being taken in defense of oneself or another but once the active threat is no longer present, that's another story. I don't like the idea that a government may execute its citizens.
I have no problem with that either. I hold individuals responsible for their actions and most every criminal is aware of the consequences of their misdeeds. I think prison should be punitive, leave rehabilitation to individuals interested enough to pursue it on their own.