The Missing Link
I disagree with the theory that theory that the Islam–Left alliance is due to common enemies. They share the same type of goal. The object is not to win (since the Forces of Good will win in any case) but to be the instrument of the inevitable victory. The science-fiction writer Olaf Stapledon noticed a similarity between Communists and some types of religious fanatic several decades ago:
… Funny too, what a religious fellow that Communist really is. Of course, he doesn't know it, and he hates the word. Says men ought to care for Man and nothing else. A moral sort of cove, he is, full of ‘oughts.’ Denies morality, and then damns people for not being communist saints. Says men are all fools or knaves or wasters unless you can get 'em to care for the Class War. Of course, he tells you the Class War is needed to emancipate the Workers. But what really gets him about it isn't that. The fire inside him, although he doesn't know it, us a passion for what he calls dialectical materialism, for the dialectic of history. The one selfishness in him is the longing to be an instrument of the Dialectic, and oddly enough what he really means by that, in his heart of hearts, is what Christians so quaintly describe as the law of God, or God's will. Strange! He says the sound element in Christianity was love of one's fellow men. But he doesn't really love them, not as actual persons. He'd slaughter the lot of them is he thought that was part of the Dialectic of History. What he really shares with Christians, real Christians, is a most obscure but teasing, firing awareness of something super-individual. Of course, he thinks it's just the mass of individuals, the group. But he's wrong. What's the group, anyhow, but just everybody lumped together, and nearly all fools or limps or knave? It's not simply the group that fires him. It's justice, righteousness, and the whole spiritual music that ought to be made by the group. Damed funny that! Of course, I know all Communists are not religious, some are merely—well, like that bloody little man the other day. But this fellow is religious. And so was Lenin, I guess. It's not enough to say his root motive was desire to avenge his brother. In a sense, that's true. But one can feel behind nearly everything he said a sense of being the chosen instrument of Fate, of the Dialectic, of what might almost as well be called God.(from Odd John).
Other religions have similar ideas (Stapledon mentioned Christianity), but in Islam the idea of submitting to God's will is primary. If God has decided everything with no room for free will, there isn't much point in deciding not to dive bomb the World Trade Center since God has already decided whether or not it will happen.
This also accounts for the odd imperviousness to past failures. Any past failure by Muslims (or leftists) simply means that the Muslims/leftists in question weren't true instruments of the victory of God/dialectic. If nationalists failed, that meant they weren't true Muslims. If eugenicists failed, that meant they weren't true leftists.