There's this saying that, In the right circumstance, Everyone is capable of just about anything.
I think that is true. But no matter what we may do, We'll never think it's right. So if I am forced to kill someone, I'll never ever think it was the right thing to do, Regardless.
I think that can apply to bad things and bad people. No matter what you do, They'll never see what they did as wrong, And they'll always be prepared to do it again.
So how do you believe people who are never sorry, never repentant, never changing, should be dealt with? Their hearts will forever be, in a sense, evil. So how do you justify a finite sentence?