At the height of the war in Lebanon two months ago, an assortment of Arabs, British Muslims, radical socialists and bleeding heart liberals marched through the streets of London with placards proclaiming "we are all Hezbollah." Since Pope Benedict XVI delivered his scholarly but contentious lecture in Regensburg last Wednesday, an equally unlikely assortment of individuals bound by a common distaste for Islamist terrorism have been whispering the counter-proclamation: "We are all Papists now." Before rushing to take rival positions in the trench warfare of civilisations, it is prudent to remember that the contemporary Islamist assault on the "decadent" West,...