Tarek Fatah an outspoken progressive Pakistani-Canadian Muslim explained in an interview how Islamic bankers have sold Muslims a bill of goods which has kept the majority of Muslims poor and enriched a minority. He says most Western banks now offer "Islamic" banking because it is incredibly profitable.
Fatah belongs to the Canadian Muslim Congress which is vocal opponent of conservative/fundie Islam. Below is an excerpt from an article about "Islam" banking from that site.
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Explaining the deceptive workings of interest-free Sharia banking, as practiced by Saudi and other Islamic banks, Ms Hassan said: "Muslim bankers and their hired clerics claim they indulge in interest-free banking, but in reality they hide this interest. So-called Islamic banking institutions claim they operate on "zero interest." However, the fundamental characteristic of charging interest is never truly eliminated in Islamic banking, but rather is hidden.
The MCC president referred the CMHC president to Muhammad Saleem, a former president and CEO of Park Avenue Bank in New York, who has written a book, Islamic Banking — A $300 Billion Deception. Mr. Saleem, who was a senior banker with Bankers Trust where, among other responsibilities, he headed the Middle East division and served as adviser to a prominent Islamic bank based in Bahrain, dismisses the founding premise of Islamic banking, saying,
"Islamic banks do not practise what they preach: they all charge interest, but disguised in Islamic garb. Thus they engage in deceptive and dishonest banking practises." http://www.muslimcanadiancongress.org/20080129.html