I am not a liberal or an atheist and I oppose the taking of all human lives because it is wrong. And that would apply to self defense or the defense of another life. Why? Because we know it is wrong because of the way it makes us feel afterwards, even if it is done in self defense or the defense of another.I oppose the death penalty. I think killing someone is wrong, unless it is in self defense or defnse of another life.
And given the number of sentences that have been reversed, the amount of corruption in the justice system and the unreliable nature of the typical witness, I don't believe you can be 100% sure you got the right person.
And I am not a liberal.
It is better to maintain the standard and admit that you failed to meet the standard rather than to justify your actions. Why? Because standards are lowered incrementally; gradually. One rationalization at a time. Once we start to rationalize the taking of one life because of one reason it is easier to make the leap to the next rationalization.
I am curious though, you are making a "we are fallible argument" as a basis for your belief. Do you oppose the state taking the life of a man guilty of a heinous crime? Because if you don't, why even make that argument?