I don't see what you're getting at. Certainly Europe's religious wars are a prime example of what I'm talking about: the idiocy of religion-based murder.
BTW, you may have missed it, but you made an appeal to morality in justifying your thought that killing is bad.
This belief is axiomatic in the conversation. I would hope that both of use believe that unjustified killing is wrong, regardless of why we believe that.
So, why should we set an axiom that killing each other is bad? Don't you taste good or what.