Considering there is no danger in keeping murderers in a maximum security prison, the only reason the death penalty exists is for sadistic revenge purposes. This is immature of us as a society.
Even a terrible person deserves the right to change, the right to the imagination, wonder, and experience that is life (even life behind bars). Life is so fundamental to human life that it even sounds ridiculous/redundant to say so. It is inalienable and should not be taken.
Toss in the fact that incorrect convictions are possible and have happened, and the logical conclusion is: Abolish the death penalty.