I hate to break it to you, but that book you're quoting wasn't penned by the hand of God. It was written by men like you and me. You're entitled to your faith, but understand that your faith is for you alone.
Of course they're responsible. I never said anything to the contrary. But the death penalty is also murder.
That being said, everyone has a right to defend themselves, especially against a corrupted state. It is up to every man to decide what lengths he must go to defend himself and his family, violence may be justified. But don't fool yourself into thinking that someone "deserves" death.
Okay. That explains it.
As for Faith. If it is true. Then its never for the person alone. Just like Mathematics isn't for a person alone either.
If God exists his Rule extends over all people. Regardless of what they want or think.