If the Ten Commandments say “thou shalt not kill” how can a Christian fight in a war? Exodus holds the 10 commandments.  Specifically, we see:


  Exodus 20:13 (KJV)
  Thou shalt not kill.


Since the Ten Commandments say “thou shalt not kill” why do many Christians fight in a war?

Note this question is not aimed at pacifist denominations, but at those who do support war (at least in some situations).
This misinterpretation is due to a language shift since the days of King James, when that version of the Ten Commandments was set forth.  The term "kill" back then meant what "murder" means today, and I think that everyone would agree that that's a good thing to prohibit in strong, absolute terms.

If you look through the King James Version of the Bible, you don't see the word "kill" used very often, and when it's used it invariably refers to murder.  For a non-murderous cause of death, the word is "slay".  This is what soldiers do to each other, and if I recall correctly it's also what the priests did to the sacrificial animals.