Fascinating. I'm certainly not Muslim either, but I do find their system of legal rulings to be quite interesting, as well as their efforts at creating alternative approaches to banking. Have not previously seen it discussed how cryptocurrency fits into that framework.

I would note, however, that currency was in use by the ancient Sumerians and other civilizations of Mesopotamia several thousands of years ago, whereas Islam only began some 1400 years ago. Same region of the world and possibly even some of the same ethnic groups, but currency in the Middle East predates Islam by quite a bit.

I think the concern the Turkish directorate was trying to raise is that, while fiat currency can certainly be used for illegal or harmful activity as well, there is more action that a government can take to block that action if needed. Bank accounts containing fiat currency can be frozen or confiscated by a government if necessary to halt such activity, for example. It's much harder for a government to intervene in the illegal use of a cryptocurrency. Opinions can certainly differ on whether that's a bug or a feature of cryptocurrency; the Turkish government, understandably, sees it as a problem.