Re: a, yes, death is final. However, say someone is sentenced to life and his innocence is discovered 20 years later. How do you correct that miscarriage? Pay him off? Does that make things right? How much is 20 years worth?
In a justice system, it is imperative that people weigh the evidence carefully and only convict when it’s beyond a reasonable doubt. That is the case regardless of the punishment. The fact that some innocent get punished and some guilty go free is an indictment of what takes place in the court room, at the crime scene, etc, not of the punishment itself.
Furthermore, one of the reasons death row inmates can end up costing the state more than a lifetime prisoner is because of the extensive appeal process available to them to help ensure it is not a wrongful execution (though it is admittedly not a foolproof process).
Re: b, most importantly, this is not a prohibition of all taking of human life. It is the prohibition of murder. The very same law in the OT authorizes the state to take the life of certain criminals (including that of murderers).
I’d like to further point out that the ten commandments are a part of a covenant or a contract that God had with the Israelite people thousands of years ago. While some of the same principles may still apply, we are not bound to them anymore than citizens of Japan are bound by laws in Chile.
I am a Christian, but I prefer not to make religious arguments that I think should be binding upon non-Christians. I find my libertarian leanings to be congruent with God’s law, but I don’t expect people to adopt them for that reason.
I’m not sure I follow you on your thoughts about death being “the easy way out.” If the point of punishment were strictly to make the guilty party suffer, then we wouldn’t have a “cruel and unusual punishment” clause. At any rate, it seems like you don’t want to extend mercy to the guilty (via the death penalty, presumably because you want them to suffer?). But then you note that those with life imprisonment have the opportunity to repent (which I’d think would make it a better way to go). Though I’d like to point out that a) people on death row have the opportunity to repent as well and b) someone’s faith decisions or lack thereof are not the concern of the state. The state, from the Christian perspective, is an institution in place to punish wrongdoers and protect the innocent. It is a tool of God to provide a measure of justice and order for the time being, as imperfect as that may be. Christians are told not to return evil for evil because vengeance belongs to God right before Paul goes on to explain one way in which God takes vengeance (i.e., the state). Mercy is the duty of the church.
I think that victimless crimes (mostly have the War on Drugs in mind here, though prostitution, gambling, etc apply as well) should not be the concern of the state, and it’s a shame that the government is housing them all for personal choices they have made. However, the fact that government wastes money in one area does not justify it wasting money in another area either.
My biggest concern when it comes to the justice system isn’t the choice btwn life imprisonment (is that kidnapping btw? if capital punishment is murder…) and the death penalty. I’m more concerned about whether the guilty are being charged and punished or not and whether the innocent are being released or not. People rely on “expert” testimony on arson, DNA evidence and its interpretation is taken to be infallible, plausible motive is treated as damning, etc. Not to mention trials and punishments string along months and years after the act. If this stuff was straight, I’d have an easy time advocating the death penalty in murder cases where the defendant’s guilt was beyond a reasonable doubt. As it stands, given the corruption and incompetence that run rampant, I’m less eager to cry for blood.