The claim that Islamic banks assume a greater risk is also disingenuous. The most striking thing about the four main modes of sharia financing — mudaraba, musharaka, ijara and murabaha — is how little they differ from conventional finance systems. The first two offer the same services as venture-capital industries where an entrepreneur borrows money from an investor for a specific project and, if successful, returns a pre-agreed percentage of the profits. However, they account for only a very small percentage of the business of Islamic banks.

Ijara is the second most popular Islamic financial service and, like the rest, it bears a startling resemblance to a service that has long been in place: lease financing. This form of lease financing claims to be sharia-compliant because of the risk taken by the bank in itself owning the equipment (for example, a car) that it is leasing to its client. However, in reality, Islamic banks take very little risk as they require their clients to pay a premium for insuring the item and usually the client must also make an upfront payment of a certain percentage of the cost of the equipment.

Under murabaha, which constitutes the main business of Islamic banks, the bank buys goods at the request of a client and sells them the goods at a profit. This extra payment by the client is not labelled as interest, but rather as a "mark-up" or "service charge". Islamic banks claim that this ensures that the bank shares the risk with a client because it initially takes ownership of the goods before they are transferred. However, in order for the murabaha to be legitimate, this ownership need only last for seconds and indeed rarely continues beyond that. The leading economist and expert on sharia finance Timur Kuran is right when he describes murabaha as a "technique that is nothing but interest concealed in Islamic garb". This then raises the question: if the difference between Islamic and conventional banking is negligible, what is the point of it?

The first detailed and comprehensive argument for the creation of a sharia-based financial system was articulated by the Pakistani journalist and thinker Sayyid Abul-ala Mawdudi (1903-1979), one of the godfathers of modern jihad and the founder of the Jamaat e-Islami (JI). For Mawdudi, the answer to the perceived ills of Muslims around the world was to be found in a return to the days of Muhammad. He identified western concepts, particularly secular liberal democracy, as an existential threat to the umma (the worldwide Muslim population, conceptualised as a monolithic political bloc) and his answer was twofold. First, Muslims had to identify themselves first and foremost by their religion and therefore separate and isolate themselves from the "unbelievers". Second, Muslims had to engage in jihad to reclaim formerly "Islamic lands" and eventually establish global supremacy. Mawdudi believed that Islamic finance was one of the essential cogs of a totalitarian Islamic state.

This notion was quickly taken up by Sayyid Qutb (1906-1966), one of the founders of the Egyptian Muslim Brotherhood, widely recognised as a direct inspiration for al-Qaeda. The fact that Islamic economics offered very little change in practical terms was of little significance to Islamist ideologues such as Mawdudi and Qutb. It was simply yet another way of Islamising Muslims and presenting the West as evil, avaricious and corrupt.