If one sentence summarises the mood of this year's Edinburgh Fringe, it is this earnest pledge, muttered by a Bushalike President as he orders a new terror raid: "I have to keep killing religious fanatics. God told me to."
The terrific comedy twosome Toulson and Harvey have perfectly summarised the suspicion in Edinburgh that the world is choking on converging toxic clouds of religion, wafting in from the West - where there is a Christian fundamentalist president who believes stem cells are people - and even more speedily from the East, where Islamic fundamentalists believed blasting 4,000 infidel out of the sky last week would put them on an escalator to virginarama. This year's Fringe is filled with newly energised atheists, offering ironic points of darkness as their answer to this blaze of fake light.
A few brave Muslim and ex-Muslim comedians are standing up to the death-threaters and the head-hackers. This should, for example, be Omar Marzouk's year, since, as a Danish-Muslim comedian, he has a unique take on the fever that broke over the Muslim world when a clutch of Danish cartoonists dared to draw Mohamed.
"It's hard enough being Muslim, but now one billion Muslims hate me for being Danish too," he says. "I'm a buffet of hate. It's hard figuring out what to boycott and what to burn." But his latest show is a surprisingly stale rehash of last year's gags. It is still politically brave: he militantly defends free speech, and while he savages "Israel's precision bombs that hit random targets", he also points out that "nobody kills more Muslims than Muslims at the moment". But his joke-death ratio is worrying - although he does quip: "I don't mind when my jokes die because they go to heaven and get 72 virgin jokes."
As so often, the bravest, smartest critic of Islamic fundamentalism in town is a woman the fundamentalists would love to claim as "one of ours" and enslave. Last year it was Shazia Mirza; this year it's Shappi Khorsandi. She is a jangly bundle of unveiled nerves whose show, Asylum Speaker, is both adorable and daring, a rare combination. "I'm a female Iranian stand-up," she says as she enters. "They call me the box-ticker." ("You might find it difficult to tell the difference between Iran and Iraq," she adds. "We're the ones with weapons of mass destruction.")
Shappi is one of the millions of children of the Islamic revolution who - in the face of the Iranian mullahs' theocratic repression - have become the most articulate, committed atheists in the world.
She finds it grating when people tells her she wears "Western dress", noting, "Western dress is a 10-gallon hat and cowboy boots. Anything else is just clothes." She is angry that a thousand people on the Fringe ridicule Christianity, but she is the only one taking on Islam. "Nobody holds off from mocking the Christians, saying, 'Oooh, we don't want to get on the wrong side of Cliff Richard. He might croon us to death'."
While she is sympathetic to Muslims suffering from stupid social prejudice - "I have a cousin called Mohammed. He shortens his name to 'Don't shoot'" - she has lashings of righteous contempt for fundamentalists like "that 14-year-old girl who went to the High Court to fight for her right to go to school wearing her sleeping bag".
Her courage comes from a childhood hiding from the assassins of the Ayatollah Khomeini. Her father is one of Iran's most famous satirists who was first sent into exile for criticising the fascist Shah, a dictator helpfully funded and armed by our governments. "When the revolution came, he headed home saying 'Woo-hoo! The Shah's gone! I've got some great Ayatollah jokes!'" But the fundamentalists quickly hijacked the rebellion of the Iranian people - "they love hijackings" - and he was declared an Enemy of Islam. "I wanted to say to them, look, my dad's 5ft 2in and he can't swim. You don't need a fatwa - just build a moat," Shappi says.
The Khorsandi family lived in hiding in the UK, and Iran's loss was our gain. Most stand-up comedy shows in Edinburgh are 20-minute comedy spots stretched out for an hour, making them formless and baggy. Shappi is a rare example of a comedian who actually works much better in an hour-length show, where she can build a narrative and an argument. She is as brilliant at puncturing prejudice against refugees as she is at puncturing the poison of the mullahs.
To people who say Britain is full, she says, "I live in Brixton and I happen to know there's a flat going under me." To people who say she must have split loyalties, she answers with the sweet irony, "If England played Iran at football, I'd back Iran - because I'm English and I support the underdog." Trapped in exile, Shappi - like millions more Iranians - dreams of an Iran that would "boldly threaten to wipe Israel - off the Christmas card list."
Christian fundamentalism is just as ridiculous, but less likely (for now) to respond with barbarous violence. That's why, all over this old Scottish town, there are nightly Raptures. At least five shows depict the ultimate climactic moment in fundamentalist Christian eschatology, when the Lord will drag his physical army of the faithful up to Heaven and leave us godless dogs here on Earth to survive a thousand-year war with Satan.
The most original - and weirdly compelling - Rapture is in Hillary Agoniste at C Venues, written by Nick Salamone. It's 2009, and President Hillary Clinton is in charge when, one bright American morning, 1 per cent of the world's population simply disappear. Once the scientists can offer no answers - not even Stephen Hawking, in a lengthy cameo - the military lobby President Hillary hard to blame space aliens. They need to calm the Christian heartland heart attacks, caused by horror at the thought that they have been Left Behind while the heathen likes of Bill Clinton, Jane Fonda and Kim Jong Il have been hoovered up to Jesus. "So long as Bill is one of the rapt, they will never accept this is a Rapture," says Hillary with bleak reassurance.
It sounds like the set-up for a jaunty Christopher Buckley novel, and Salamone does indeed milk humour from his lactating premise. The foaming fundamentalist Pat Robertson is picked up by satellite navigation dumping his car and clothes by the side of the road, putting on a fake beard and cycling off in an attempt to convince his followers he was one of The Chosen.
The play becomes blacker and blacker as it progresses, avoiding the obvious gags for a surreal character study of Hillary Clinton, played by Nancy Lineberg. Confronted with nuclear Armageddon in the Middle East, Hillary begins to see - or hallucinate - the Angel of Death, warning that she is in charge "not of the cradle of civilisation, but its grave".
Hillary's much-rumoured, little-seen liberalism burns away, and the scared Christian girl with Nixon-loving Republican parents remains as the Commander-in-Chief of a disintegrating country. When a fundamentalist preacher snaps to Hillary's Scottish Press Secretary, "You Europeans still insist on living in a world of reason. Your reality-based Rasputins are as dead as Descartes and Rousseau. Your Enlightenment has dimmed. This is a world beyond reason", Hillary seems to agree. "I will not be the Whore of Babylon," she says, announcing this is indeed the Rapture. It's a bizarre fable with plenty of flaws - it feels like a first draft that needs to be tightened and gagged up - but as an ironic comment on the religious logic that underpins even swaths of American liberalism, it has quiet, horrible power.
There's a more sunny Rapture over at the Traverse. As soon as you enter Particularly in the Heartland, you are greeted by a shiny happy cast of American twentysomethings who - in classic Brechtian style - make you immediately aware of the illusory nature of their performances. They sing patriotic songs, offer you a hymn sheet for "The Battle Hymn of the Republic", and chat about the Californian home-towns in which they live as actors. Already you can see something is wrong - one of these smiley people is pregnant and covered with blood stains. You soon discover these are the dishevelled ranks of the Left Behind - and they include the ghost of Bobby Kennedy, preaching lost liberal sermons to his depleted flock.
Like Salamone, the New York-based Theatre of the Emerging American Moment (TEAM) are inhabiting the mental landscape of the Christian evangelicals in order to subvert it. The post-Rapture wilderness they depict with feverish brilliance is a reminder of the psychotic sadism of the Christian God as depicted in the Bible, a monster who feeds small children to bears and "laughs at your calamity". It's chaotic but hypnotic. At times it's too obviously the work of a devising team rather than a single clear intelligence, not least when it is laden with obvious imagery - this is Kansas, so here's Dorothy. But as you leave the theatre, you feel as if you have just been possessed by a demon with perfect white teeth and perfect white Christian theology.
But can the strain of witty atheism on offer on the Edinburgh Fringe ever douse the great fire of religion currently consuming whole continents? I hope - but certainly don't pray - so.