The Bible plainly states, "Thou shalt not kill," yet so many Christians favor the dealth penalty.. Why?

The English language has more words than most all the other languages and yet we only have a limited amount of words to express ourselves properly. It is true the type of word used is in referance to murder or to kill in hatered, vencence, or the heat of the moment. When originally translated murder was not a popular term but to kill was used for a lot of different things, so the word kill became the one used.
As far as Christian in favor of the death penalty, I know just as many if not more so against it than for it. I personally believe if used properly it could be a drastic deterant to the most violent crimes. If you commit a hienous crime and just get to sit in a hotel for years on end with a possiblity of getting released that might make it worth it, if you also may lose your life than it takes some more consideration.

because they don't have love!

Good question. I've asked it a million times myself and never got a satisfactory answer.

Yes, the translation is clearly dorked up, or else we would not eat meat, exterminate insects, or drive cars that could run over people's pets accidentally. From the Hebrew, the word can mean either kill or murder, but murder is the more appropriate translation based on the original intent (remember the OT saying "eye for an eye"). And murder is defined as killing without a morally justifiable reason. Hence the huge number of religious moralists in support of the death penalty...

um...I'm not one of them, by the way...

Because christians are hypocrits, favouring the passages that fit their agenda and ignoring the rest.

whatever is wrote, will be interpreted different every time. there are millions of people that only do that: turn words up side down, to make it have sense.
as if "Thou shalt not kill" means "no killing without a morally justifiable reason", then i can morally justify about every single murder ever happened on earth, so we can kill freely with no problems. well, the laws are a bit better in this matter.