"Christians" Who Support the Death Penalty

If I believe that I was properly subject to the death penalty for my many sins, and that I was spared only by the grace of God through the execution of Jesus, what sense does it make for me to be pro-death penalty, much less to rejoice in the horrors of a botched execution? It seems to me that quite a few self-professed Christians have not given much consideration to the implications of some of the most basic tenets of their faith. According to the Man himself, a condemned person who has been showed mercy is in a poor position to insist on harsh punishment for another condemned person.

"[T]he kingdom of heaven may be compared to a king who wished to settle accounts with his slaves. When he had begun to settle them, one who owed him ten thousand talents was brought to him. But since he did not have the means to repay, his lord commanded him to be sold, along with his wife and children and all that he had, and repayment to be made. So the slave fell to the ground and prostrated himself before him, saying, 'Have patience with me and I will repay you everything.' And the lord of that slave felt compassion and released him and forgave him the debt. But that slave went out and found one of his fellow slaves who owed him a hundred denarii; and he seized him and began to choke him, saying, 'Pay back what you owe.' So his fellow slave fell to the ground and began to plead with him, saying, 'Have patience with me and I will repay you.' But he was unwilling and went and threw him in prison until he should pay back what was owed. So when his fellow slaves saw what had happened, they were deeply grieved and came and reported to their lord all that had happened. Then summoning him, his lord said to him, 'You wicked slave, I forgave you all that debt because you pleaded with me. Should you not also have had mercy on your fellow slave, in the same way that I had mercy on you?' And his lord, moved with anger, handed him over to the torturers until he should repay all that was owed him. My heavenly Father will also do the same to you, if each of you does not forgive his brother from your heart." (Matt. 18:23-35).