There is no post-religious rhetoric that can properly meet and combat an offense such as ISIS. What shall we say, that they hate freedom? That they have a flagrant disregard for human rights? That they are guilty of war crimes? It would be true, of course, but true in a language that that bears no weight on the theocratic perversion that currently struts its self-obsessed pageantry on the international stage.

How, in short, does one properly insult ISIS? With bombs, yes, but I want an answer beyond cynicism, one that addresses how we confront this evil for ourselves, in the language of our own thoughts and conversations, private and public. Shall we strike terror in their marrow by hurling half a dictionary of liberal-democratic insults, boldly calling them fascists, totalitarians, or if we’re really feeling testy, religious fanatics and ultra-conservative, neo-nationalist Islamist extremists? Good God, it makes one feel weak and paltry just toying with the phrases. They pull 21 Christians from their homes and, with all the preening vanity of a pubescent middle-schooler with a pathological addiction to selfies, make a video of their beheading. Somehow hurling “fascist” into the abyss seems about as piercing as “bad guy.” Suddenly our indignation that they are “intolerant” is about as striking as mentioning that they haven’t developed a taste for French impressionism.

A post-Christian world has no vocabulary with which to insult a barbarian horde — or, to be more precise, a techno-barbarian Twitter account from the more predictable bowels of Hell. We have no concept of a theology as a dominant, motivating force, no concept of divine revelation as a dominant justification — we are so busy deploring the evil-justifying tendencies in religion that we have become blind to the fact that only a fundamentally religious worldview can meet, insult, and reject a perversion of religion.

If ISIS are a ‘terrorist organization’ and an ‘extremist group,’ then our insults and indignation, while they might assuage our need to cry out, are simply fuel for the fire: We say “war crimes,” and they say “yes,” we say “terrorism” and they say “you haven’t seen anything yet.” But if ISIS are a heresy, their spiritual rejection and condemnation can only come from religion. Heresy is crushed by orthodoxy, not by the emperor (or any other secular institution). Though we may continue to deplore ISIS’s screech that ‘God is on our side’ with calls of ‘theocrat’ and ‘fascist,’ we should remember: Messages can only be understood and countered in the mode in which they are given. Meeting a religion of death with a vague liberal humanism is about as rhetorically sufficient as meeting an insult to your mother by seeking to prove, scientifically, that the insult could not be true. A perverse theology is met by a real theology: God is not on your side, He is with His Church, and He will wreak terrible justice on the wolves who seek to scatter His flock. Your god is not God, he is an ‘it,’ an idol, snapped in half by the living God. Your name is cursed. Your creed is a creed of demons. You use ashes and ghosts to fortress your vanity; your moronic, masturbatory TV-drama of death. You oppress the poor, the widow, and the orphan, and your sins cry to Heaven for vengeance. You have no god, neither in your theology nor in your heart, and your fate is the fate of the godless. Repent of your sins and be saved.

Such speech would hardly do for our politicians, but it is the only speech I have found properly satisfies a a spiritual need to confront the murderers we cannot fight, a rhetoric alongside of which the rhetoric of post-Christianity appears wasted and wan.