Arguments against the death penalty
Many christians believe that they should believe people should be giving a second chance like Jesus said. He rejected the lex talionis and the Gospels record many instanced in which he forgave others, such as the adulterous woman.
Also most murders are 'spur of the moment.' State sanctioned killing only serves to endorse the use of force and to continue the cycle of violence. There is also the possibility of executing the innocent (e.g. Timothy Evans - wrongfully accused of murdering wife and infant).