Why many do religious ppl who support being pro life still support the death penalty, when it's still killing?

Many religious people say abortion is akin to taking a human life, but still supprot the death penalty. Killing someone, even if they were murderers, doesn't absolve the fact that you're still killing, and committing a murder. Thus, why the double standards? A life is a life, is it not? Especially since God is so forgiving?