The resemblance between the two movements covers far more than the speed and extent of their conquests. It can be argued that in some measure both are great Christian heresies. And like Communism, the Moslem faith in its relations with Europe has tended to follow the pattern of relentless pressure on all weak points and undefended frontiers and to advance its banners wherever there were found to be no defenders at the gate.... Islam derived its power to attract educated and intellectual groups from the use it made of ideas deeply congenial to the Oriental mind. Its rejection of the Greek and Christian heritage of humanism and incarnation in favor of a purely transcendent deity accorded well with the other-worldly tradition of Oriental religious thought. At the same time, the Moslem appeal to the people at large lay in the social evils which it promised to redress. Mohammedanism was in part a harking back to traditional intellectual and religious ideas, in part an outburst of social protest against an unjust and unstable social order. Modern Communism has something of the same character.