The Koran’s command about there being no coercion in religion was cast aside, and Islam in its Arabian environment came to be inseparable from the power and sweep of the sword. It was the nature of these wars, brutal and mercilessly fought, that established the rule of force and terror in coercing submission to God. And it was this culture that shaped the practice of Islam and the religious attitude of the Arabs in the immediate period after Muhammad.
Since then, the Arabs — and through their influence, non-Arabs, as well — have come to conceive of Islam more as a collective identity of a people (in modern terms, nationalism), rather than the personal faith of individuals.
Under the authority of the caliphate in the first two centuries of Islam, a legal system, sharia, was elaborated by religious scholars. It served the interests of the power-holders. But as Tunisian scholar Mohamed Charfihas noted, sharia was “based on three fundamental inequalities: the superiority of men over women, of Muslims over non-Muslims, and of free persons over slaves.”