Han kaller seg bare «Abbas». Han ble født i Iran for 65 år siden og kom til Frankrike som liten gutt. Han er profesjonell fotograf og har dekket mange kriger og konflikter. Han var troende muslim, men regner seg nå som ikke-troende. De siste syv årene har han reist rundt i 16 muslimske land. Han ville forstå og registrere den mulimske verdens reaksjon på 9/11. Resultatet er blitt boken In Whose Name? The Islamic World After 9/11. Han fant mange bortvendte ansikter, både overfor terroren og en krypende islamisering. Det er uttrykket han bruker. Myndighetene bekjemper jihadistene. Men islamiseringen greier eller vil de ikke gjøre noe med. Islamistene vinner hearts and minds, og myndighetene tar ikke et oppgjør som ville bli ubehagelig fordi det måtte omfatte fortolkningen av Koranen.

Han spør seg hva som får mennesker til å anta skikker og følge regler som strider mot det som er naturlig i det klimaet de lever i: som de badende på en strand i Indonesia. Der bader kvinnene heldekket, hvor de tidligere var iført badedrakter. Det samme gjelder tildekking av kvinner i Afrika. Dette er islamiseringen i praksis.

Now a non-believer, he laments what he sees as the «intellectual stagnation» of Islam, the «arrogance» of a religion that welcomes converts but considers it lawful to behead apostates, the way many of its followers are locked in the past. At one point he discovers the writings of Henri Michaux, a Belgian: «At last I’ve found a traveller… who doesn’t feel compelled to like the inhabitants of the countries he visits.»

Abbas’s argument is not with Islam, but with the Islamists – the political ideologues who have hijacked the faith, and the jihadists who use it to justify their violence. He decries the «creeping Islamisation» he found in almost every country – the building of ever more mosques, the relentless covering up of women, the censorship, the ever louder cries of muezzin calling people to prayer.

On an Indonesian beach he photographed women and children bathing fully clothed where they used to wear swimsuits: «Here we have an entire nation turning its back on its natural element, the tropical ocean, and adopting the customs of an imperialism derived from the desert.»

These are symptoms of a more worrying phenomenon, Abbas believes. «What Islamists have lost in terms of military effectiveness – and they’re relentlessly hounded by all the states – they gain daily through the spread of Islamic influence and ideas.» Muslim governments may be cracking down on the jihadists, but they are losing the battle for their peoples’ hearts and minds. Most are appeasing, not confronting, the Islamists in their midst, he says. «Many states are encouraging this Islamisation. Why? Because they think if they can ride the tiger they’ll be safe. They forget that’s what Pakistan did for many years and now the tiger has turned against them.»

They should be waging intellectual war with the extremists, challenging their self-serving interpretations of the Koran, he argues. «It’s not just fighting the jihadists – that’s simple. You catch a few guys, you put them in prison, you kill them – that’s easy. But fighting an ideology which draws its justification from what you all believe, which is the Koran – that’s more difficult.»

Abbas In Whose Name? The Islamic World After 9/11 is published by Thames & Hudson on June 15, priced £29.95

Snapshots of the Islamic world