I don't see how you can argue for the death penalty. Killing people doesn't help anyone. Who has lived a happy and healthy life as a result of a death row execution of someone with a life sentence?
Run the table "CAPPUN" vs "RELIG". Nearly every major religious position in the US (including atheist/agnostic/none) is largely in favor of the death penalty, with only Muslims and Native Americans coming out as more than 50% opposed in both sets, and "other eastern" being over 50% in the newer set.
Also of note: whites are much more in favor of the death penalty than other races, Republicans are slightly more in favor than Democrats, people with higher incomes are more in favor than those with lower incomes, and people with average education (high school or 2-year college) are more in favor than those with either very high or very low education.
(I'm from a religious subgroup that's anti-death-penalty, anti-war, pro-life, etc. and I would argue that the death penalty isn't consistent with a Christian ethic, but plenty of people obviously disagree with me.)