Robert Bowers, the gunman who killed 11 worshippers and wounded six others at a Pittsburgh synagogue in 2018 in the deadliest-ever attack on Jewish people in the United States, was unanimously sentenced to death by a federal jury on Wednesday.
The death penalty isn't about punishing criminals.
Society as a whole decides that due to a person's actions and values they can no longer qualify as a person like the rest of us. To be a person you are required to value people's lives. There is no room for choice or debate about this matter, it doesn't matter what your religion or your heritage is, if you are a person, you're required to value the life of other people.
When failure cases like this guy and Dylan roof show up, we have to judge whether or not they're capable of valuing life and if they're not then they're not people. It's that simple. And if you're not a person, your livestock and human livestock is pretty damn worthless, so you might as well slaughter them on the spot.