The church has made many arguments against capital punishment (CR, Web poll). Those who do not accept the church’s moral authority in the matter should consider the following: to support capital punishment, one must either accept that the court system is infallible (which is demonstrably false), or that it is acceptable to occasionally execute innocent persons.
To be just in a fallible world, punishment must not be irrevocable. Imagine going to the death chamber for a crime you didn’t commit. Imagine your child going there.
Our society can do better. Life without parole is a severe but revocable punishment.