Tribal society and culture has many different characteristics and aspects, but one important one is that it's generally filled with revenge killings and vendettas. Mostly this takes place against nearby rival tribes but, lacking that, it happens within the group as well. The legacy of this socially destructive and personally deadly internecine competition can be seen even today in the most backward parts of the West such as Sicily, Scotland, and Appalachia.
This small-scale forerunner to war seems to be the product of a kind of pre-liberalism, pre-reason, pre-philosophy proto-morality. These vengence killings are centered around "honor," oriental-style "face," "name," and important parts of public reputation. The evil to be avoided here seems to be social and public dishonor, disgrace, disrepute, and shame. The goal here is a kind of individual pride, self-esteem, and self-respect which is obtained via respect from others or from creating social fear.
Another version of this primitive or proto-morality can be seen in today's Western street gangs. These free-floating social units exist inside the urban jungle where they seem to have about the same attitudes and motivations as the tribal savages. They seem to have the same limited, backward, primitive values and goals. Their vulgar, crude, rough Moral Code is essentially "we don't take no shit from nobody." Revenge against rival street gangs which have "dissed" (ultimately, dishonored) them is a great part of their existence.
Another instance of this primitive Moral Code in action can be seen in most wars of non-conquest. The usual cause of battle is that one nation perceives another nation to have disrespected or dishonored it. So the wounded party fights to reclaim its lost pride and perceived proper place among (usually similar and nearby) nations.
The great religious alternative to all this rather pointless bloodshed is the values and goals of Mercy, Charity, and pervasive Compassion extended toward potential and actual enemies. Religion also promotes a kind of mindless, contextless, unexplained, anti-intellectual toleration, amnesty, forgiveness, and ceasefire. This is all supposed to lead to that state of social equalibrium which is loosely known as "peace."
But such social stability and peace is neither possible nor desirable. It has never worked in human history, and the goals and ideals aren't intellectually correct. Religion doesn't lead to social harmony and peace, but rather war. This moral alternative and "improvement" over traditional tribal vendettas isn't an improvement.
The great rational or liberal alternative to all this is pure justice. This means universal, real, objective, impartial true justice, which is finely diserned and applied. A society and culture which successfully practicies and achieves this generates a kind of great benevolence, generosity, and magnanimity of spirit, attitude, and behavior in virtually all of its members.
Such things are infinitely superior to the vague, counterfeit, lowly alternative of Mercy and Charity. A liberal love of, and adherence to, pure justice leads to a kind of overflowing of the individual heart and a wish to expand and share happiness with others. Only rational philosophy and liberal justice are capable of generating a social utopia, including the religious ideal of peaceable people "overflowing with the milk of human kindness."