Western nations, whether nominally Christian or not, all claim to be civilized countries, but that is belied by the most basic of facts, that these nations do not treat their fellow countrymen, let alone those outside of their nation, with the care and consideration that would be in keeping with the mantra that all are equally created and thereby all are our brothers and sisters. In point of fact, the taking of anyone's life should be considered to be fratricide, for either you believe wholly in the gospel as written, that all thereby are brothers and sisters in God, or you do not, as there cannot be any conscious equivocation of what is a fundamental tenet of the Christian faith, for this too is consistent with basic morality, and there are none born of a lesser God.
The fact that many acknowledge that we are brothers and sisters on the one hand, but are not true brothers and sisters on the other hand, can only be explained by vilifying one's opposition, so as to make those certain people into something less than human, that is subhuman, something less than God created, and thereby something equivalent to an animal, which is why in wars, the opposition through media and images is universally displayed as some sort of savage, and referred to in terms that negate their value as humans. Although, these may be the descriptors utilized, and these may be believed by people, implicitly, literally, or not, none of this is actually true in fact.
For instance, every human being in this world, from a DNA perspective, from a biological perspective, and from a visual perspective, is, in fact, a human being, despite what religion may be their faith, despite the color of their skin, despite their language or their customs, and so on and so forth, they are all human, and to try to make them into something that equates to them a value of being less than human is to wrongly deny to them their true essence.
That is why the great human religions, the great men and women of real substance, will not take up arms against their fellow man, for they see that doing so, would be a version of fratricide, for that is indeed what it actually is. This does not mean that man has no right to defend himself, from enemies foreign and domestic, for self defense has its legitimate place, but it does mean that wars of aggression against country or neighbor cannot be right, especially when doing so, necessitates in the killing of both the "guilty" as well as the innocent.
Those that believe that it is "kill or be killed" are truly blind, for they aren't utilizing the gift of their human mind, but instead are behaving as if their mind has been subverted and has instead been taken over by their lower animalistic instincts. That is why some of the worst fratricidal atrocities are performed by those that have had their minds addled by drugs or drink or their minds somehow have become damaged or mesmerized, for to take the life of your brother and to not recognize it as such, demonstrates a callous disregard that all come from the exact same First Source, and that therefore every life taken, takes us further away from where we need to be going.