A friend recently asked me this question. Here was my brief response:
Pro-lifers assert the intrinsic value of life, which leads us to react strongly against murder, murder of innocent victims in or out of the womb. They are not making an exception to the rule or looking the other way or being driven by political expedience. Rather, it is precisely the sanctity of life which leads many in the movement to favor capital punishment for murderers; capital punishment being the clearest and severest social reaction to the taking of innocent life. So it is opposition to murder which leads many pro-lifers to be pro-life on abortion AND pro-death penalty as well. This is why, incidentally, God in the bible condemns abortion, infanticide and murder BY requiring execution of the offender. God called for capital punishment for all three as a strong expression of His love for human life (His Image Bearers). Even pro-lifers who disfavor capital punishment recognize this consistency at some level, admitting that the pro-life position most emphatically calls for the absolute protection of INNOCENT persons (fetus being the most innocent of all). The divine moral law, by the way, was prior to the giving of the Mosaic law, so it appears to be rooted in God’s creational intentions rather than the expired Israeli theocracy.
Gen 9:5 And for your lifeblood I will require a reckoning: from every beast I will require it and from man. From his fellow man I will require a reckoning for the life of man.
6“Whoever sheds the blood of man, by man shall his blood be shed, for God made man in his own image.
If a pro-life Christian is inconsistent because he expresses his love for human life by being pro-life and pro-death penalty, then God was inconsistent too. But Let God be true and ever man a liar (Rom. 3:4).
Now, this is not to say that the death penalty is always justly applied or even that it is required for ever nation-state. Christians may look at the circumstances of their own time and place and decide that capital punishment is unjustly used or applied (given to some races, for instance, at much higher rates than others; administered inhumanely, etc.). But being pro-life and pro-death penalty isn’t in principle an inconsistent position for a pro-lifer or biblical Christian.
thereformedmind 
Good post. I agree that Genesis 9 shows that the death penalty was instituted BECAUSE God valued life.
A related question is whether the death penalty is MANDATORY today because of Genesis 9 and Romans 13. I debated pastor Ron Gleason on this topic, and argued that the death penalty in the Old Testament law points to Christ’s death on the cross, and thus it is no longer mandatory today. You can listen to the debate here.
LikeLike