(1) from a Christian perspective war is objectively evil–which is simply to say that it is a depravation of or corruption of the good. It is also to say that war is always evil no matter when it takes place, who is fighting in the battle, what society it occurs in, what reasons are behind it etc.. On the other hand, from a Christian perspective, war is for the time being, necessary. This is a paradox.
(2) unlike Christians, secular humanists have no grounds for the belief that war is intrinsically evil. The closest they might come to supporting the notion that war is objectively evil is to build some sort of utilitarian argument. For instance, one might argue that war is evil because it does not bring about the greatest amount of pleasure/happiness (and the least amount of pain) for the greatest amount of people or for a society. Clearly, however, this type of reasoning does not support the claim that war is intrinsically evil. One can easily think of a multitude of ways in which war might benefit a society or group and, in many cases, bring about the greatest amount of pleasure/happiness (and the least amount of pain) for the masses. In point of fact, a secular humanist should embrace war as being an natural outgrowth of evolution. It is natures way of weeding out the weak and ensuring the survival of the strong; of building new societies and stronger cultures.
(3) a secular humanist is not in a position to claim that anything is objectively evil . . . let alone war!
(4) anyone who denies that war is evil is truly naive. I implore you to spend a week in the trenches; to see, taste, and smell the death and mutilation of human flesh; to watch as innocent lives are ripped apart; to experience the destruction of homes, of art, of culture . . . even a just war is a tragedy.
(5) justice without mercy and grace is warped . . . it is nothing more than cold revenge. Mercy and grace without justice is heartless and unloving.
(6) a just war, if it is truly just, is allowable only as a means of preservation.
(7) shall a good God allow entire societies to engage in and endorse horrendous evils without end? Is a God who allows such societies to flourish good? Shall the wicked prevail forever?
(8) if Christianity teaches that war is always evil, why does God sanction war in the Bible? The answer: we live in a fallen world. People are evil–the world is not as it should be. In such circumstances, war becomes a necessary evil. In a world containing free agents, willing evil and injustice, a just and loving God sanctions war in order to preserve mankind from utter destruction and to exact justice. However, this is only a temporary solution. God sent his Son, to die on the cross; to trample death by death; to abolish death and killing and murder forever! Through Jesus the battle has been won; war shall be no more. In this sense, Jesus is the most successful pacifist who ever lived.