I've had a lot of Christians tell me that "shall not kill" is not in the Bible -- only, "shall not murder", and since they're not subject to the jurisdiction that outlaws killing people from other countries, they're fine doing so. I mean it's where you're supposed to get slaves, so....

People believe what they want to believe most of the time. It's messed up.

There's also a lot of killing justified by whatever situation that kingdom or group is in.