This is what I hate about religion. In concept it sounds great. A bunch of rules for how to live as a good person. Sounds great right?
Well the first rule of christianity is "Thou shalt not kill".
And then you realize that the leading cause of murder on earth throughout all of history is........religious wars.
And it's all downhill from there from a hyprcritical standpoint. Religion is used more as a tool to justify ones shitty behavior, rather than a guide to prevent it.
The only good christian I know of, is Ned Flanders, and he's not a real person!
The first rule of Christianity is, "I am the Lord thy God. Thou shalt have no other gods before me."
There is no probation against killing in general in Christianity, only murder, which makes an appearance as the 5th commandment. Murder being unlawful and/or unjustified killing, so clearly wartime killing is a-okay in Christianity.
Now, you could argue that "love thy neighbor as thyself" might implicitly forbid killing, but if you start looking to Christianity for morality or even simple consistency you're going to have a bad time.