The origins of secularism in the west may be found in two circumstances—in early Christian teachings and, still more, experience, which created two institutions, Church and State; and in later Christian conflicts, which drove the two apart. Muslims, too, had their religious disagreements, but there was nothing remotely approaching the ferocity of the Christian struggles between Protestants and Catholics, which devastated Christian Europe in the sixteenth and seventeenth centuries and finally drove Christians in desperation to evolve a doctrine of the separation of religion from the state. Only by depriving religious institutions of coercive power, it seemed, could Christendom restrain the murderous intolerance and persecution that Christians had visited on followers of other religions and, most of all, on those who professed other forms of their own.
Muslims experienced no such need and evolved no such doctrine. There was no need for secularism in Islam, and even its pluralism was very different from that of the pagan Roman Empire, so vividly described by Edward Gibbon when he remarked that "the various modes of worship, which prevailed in the Roman world, were all considered by the people, as equally true; by the philosopher, as equally false; and by the magistrate, as equally useful." Islam was never prepared, either in theory or in practice, to accord full equality to those who held other beliefs and practiced other forms of worship. It did, however, accord to the holders of partial truth a degree of practical as well as theoretical tolerance rarely paralleled in the Christian world until the West adopted a measure of secularism in the late-seventeenth and eighteenth centuries.
Bernard Lewis