Does religion cause war? It is often claimed that religion is responsible for more wars, more global conflicts and more deaths than any other factor. After all, the world has seen its share of crusades, inquisitions and jihads. Enlightened, modern people assume that if we could only discard primitive religious belief, the world would be a better place. Alas, the picture is not quite so simple. "Indeed," writes Meic Pearse, "there is only one thing...