Religious war is in itself much more rational than patriotic war. I for one have often defended and even encouraged patriotic war, and should always be ready to defend and encourage patriotic passion. But it cannot be denied that there is more of mere passion, of mere preference and prejudice, in short of mere personal accident, in fighting another nation than in fighting another faith. The Crusader is in every sense more rational than the modern conscript or professional soldier. He is more rational in his object, which is the intelligent and intelligible object of conversion; where the modern militarist has an object much more confused by momentary vanity and one-sided satisfaction. The Crusader wished to make Jerusalem a Christian town; but the Englishman does not wish to make Berlin an English town. He has only a healthy hatred of it as a Prussian town. The Moslem wished to make the Christian a Moslem; but even the Prussian did not wish to make the Frenchman a Prussian. He only wished to make the Frenchman admire a Prussian; and not only were the means he adopted somewhat ill-considered for this purpose, but the purpose itself is looser and more irrational. The object of all war is peace; but the object of religious war is mental as well as material peace; it is agreement. In short religious war aims ultimately at equality, where national war aims relatively at superiority. Conversion is the one sort of conquest in which the conquered must rejoice.
In that sense alone it is foolish for us in the West to sneer at those who kill men when a foot is set in a holy place, when we ourselves kill hundreds of thousands when a foot is put across a frontier. It is absurd for us to despise those who shed blood for a relic when we have shed rivers of blood for a rag. But above all the Crusade, or, for that matter, the Jehad, is by far the most philosophical sort of fighting, not only in its conception of ending the difference, but in its mere act of recognising the difference, as the deepest kind of difference. It is to reverse all reason to suggest that a man’s politics matter and his religion does not matter. It is to say he is affected by the town he lives in, but not by the world he lives in. It is to say that he is altered when he is a fellow-citizen walking under new lamp-posts, but not altered when he is another creature walking under strange stars.
— The New Jerusalem (1920).