Do not confuse your opposition to the death penalty with Christianity. "An eye for eye" is the biblical prescription.
As far as the death penalty goes, the fight is not between the Christians and non-Christians or the moral vs. the immoral. It's between the coddlers and the justice dispensers.
And DNA has given us powerful new ways of making sure that the guilty can be identified, ending some of the concerns of the past.
I'm not going to turn this into a death penalty debate, but it is decidedly un-Christian to take pleasure and glee from the suffering of others, period.
Besides that, I will leave you with a quote from the Sermon on the Mount; you know, pretty much the foundation upon which Christianity rests:
5:38-5:39
Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth:
But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.