When someone takes another's life, is he being hateful or loving? Is he being mean or kind? Is he being merciless or merciful? Depending on how you answer those questions, will reveal a great deal about whether you think about those subjects with sentimentality or not. The Scriptures are absolutely clear that not every instance of taking a life is necessarily bad. Taking the life of an innocent person (especially the unborn) is always evil. Yet, the picture we are given in Scripture of taking the life of a person who is guilty of certain sins is not portrayed as the evil that many sentimental people think it is.
How do we think of it when God takes the life of another person? Do we "tolerate" that because He is God and we do not have a good reason to criticize Him? In Scripture we are told, many times, that God takes people's lives. He is said to "smite the first born of Egypt", to "overthrow Pharaoh and his host in the Red Sea", and to "smite great kings" (Psalm 136). That is not all, however, because in the very same verses that tell us of these "killings" by our Lord, we are also told that He does it because "His mercy endures forever". Mercy, not justice; mercy towards His faithful, justice towards the evildoers.
When God destroys infidels (whether by His own hand or by the hand of righteous executioners) do we really see it as merciful? Our Lord sees it that way, and He tells us that we need to have the same perspective. It is pusillanimous to imagine (or even desire) that God is always "nice" to everyone. When He destroys evil it is not Him being harsh or cruel; it is merciful. We should presume this to be a fact; what else could a righteous and holy God do but to be merciful and destroy that which harms His own faithful children?
It is only a spiritually immature mind that cannot grasp that it is good for the whole world to have evil rooted out and destroyed. When God sends people to Hell it is not because He enjoys their misery. No, it is rather because He is being merciful to those who were faithful and truly desired to be with Him for all eternity. We must acknowledge that there is nothing to like about anyone suffering. And when we do, we can also acknowledge that there is nothing to like about the suffering of the righteous, either. Jesus Christ is the Judge of all men, and He casts out the evil to show mercy upon the good.
This should lead us to the understanding that it is childish and simplistic to claim that it is always wrong to use capital punishment. It is more an issue of being sentimental and confused about what is truly godly and holy. This position blurs the lines between innocence and guilt. Those who try to equate ending the life of an innocent with ending the life of a gravely impenitent sinner are displaying a certain ignorance about what is truly involved in this subject. It would be just as wrong to say that there is no difference between stealing a million dollars and taking a gun away from a murderer.
God is always merciful, but not merciful to all. Those whose lives are ended by the justice of God are receiving justice, not mercy. Those who are penitent and cry out for mercy, experience their deliverance from the hands of the impenitent. God shows them mercy. There is no other way to view rightly what God is doing when He brings down His just punishments upon those who reject His mercy. We all either stand in the mercy of God or the justice of God. Let us seek His mercy, and beseech others to do so as well.