Why don't leftists -- who obviously do not share the characteristic values and beliefs of Islamists -- grant what is spectacularly obvious to everyone else, namely, that radical Islam poses a grave threat to what we in the West cherish as civilization, which includes commitments to free speech, open inquiry, separation of church and state, freedom of religion, freedom to reject religion, and so on? In particular, why don't leftists recognize the grave threat radical Islam poses to them? Why do leftists either deny the threat or downplay its gravity?
Here is a quickly-composed list of twelve related reasons based on my own thinking and reading and on discussions with Peter Lupu and Mike Valle. A work in progress. The reasons are not necessarily in the order of importance. I suspect that each of them has a role to play in a complete explanation of why leftists are soft on radical Islam.
1. Many leftists hold that no one really believes in the Islamic paradise. The expansionist Soviets could be kept in check by the threat of nuclear destruction because, as communists, they were atheists and mortalists for whom this world is the last stop. But the threat from radical Islam, to a conservative, is far more chilling since jihadis murder in the expectation of prolonged disportation with black-eyed virgins in a carnal post mortem paradise. For them this world is not the last stop but a way station to that garden of carnal delights they are forbidden from enjoying here and now. Most leftists, however, don't take religion seriously, and, projecting, think that no one else really does either despite what the religionists say and (according to leftists) pretend to believe. So leftists think that jihadis are not really motivated by the belief in paradise as pay off for detonating themselves and murdering 'infidels.' In this way they downplay the gravity of the threat.
This is a very dangerous mistake based on a very foolish sort of psychological projection! Conservatives know better than to assume that everyone shares the same values, attitudes, and goals. See Does Anyone Really Believe in the Muslim Paradise? which refers to Sam Harris's debate with anthropologist Scott Atran on this point.
2. Leftists tend to think that deep down everyone is the same and wants the same things. They think that Muslims want what most Westerners want: money, cars, big houses, creature comforts, the freedom to live and think and speak and criticize and give offense as they please, ready access to alcohol and other intoxicants, equality for women, toleration of homosexuals, same-sex 'marriage' . . . .
This too is a very foolish form of psychological projection. Muslims generally do not cherish our liberal values. What's more, millions of Muslims view our in some ways decadent culture as an open sewer. I quote Sayyid Qutb to this effect in What Do We Have to Teach the Muslim World? Reflections Occasioned by the Death of Maria Schneider.
3. Leftists typically deny that there is radical evil; the bad behavior of Muslims can be explained socially, politically, and economically. The denial of the reality of evil is perhaps the deepest error of the Left. And so the beheadings, crucifixions, and other atrocities committed by ISIS and other Muslim savages are not expressions of radical evil, but reflective of contingent and ameliorable states of affairs such as a lack of jobs.
4. Leftists tend to think any critique of Islam is an attack on Muslims and as such is sheer bigotry. But this is pure confusion. To point out the obvious, Islam is a religion, but no Muslim is a religion. Muslims are people who adhere to the religion, Islam. Capiche?
When a leftist looks at a conservative he 'sees' a racist, a xenophobe, a nativist, a flag-waving, my-country-right-or-wrong jingoist, a rube who knows nothing of foreign cultures and who reflexively hates the Other simply as Other. In a word, he 'sees' a bigot. So he thinks that any critique of Islam or Islamism -- if you care to distinguish them -- is motivated solely by bigotry directed at certain people. In doing this, however, the leftist confuses the worldview with its adherents. The target of conservative animus is the destructive political-religious ideology, not the people who have been brainwashed into accepting it and who know no better.
5. Some leftists think that to criticize Islam is racist. But this too is hopeless confusion. Islam is a religion, not a race. There is no race of Muslims. You might think that no liberal-leftist is so stupid as not to know that Islam is not a race. You would be wrong. See Richard Dawkins on Muslims.
6. Many leftists succumb to the Obama Fallacy: Religion is good; Islam is a religion; ergo, Islam is good; ISIS is bad; ergo, ISIS -- the premier instantiation of Islamist terror at the moment -- is not Islamic. See Obama: "ISIL is not Islamic."
7. Leftists tend to be cultural relativists. This is part of what drives the Obama Fallacy. If all cultures are equally good, then the same holds for religions: they are all equally good, and no religion can be said to be superior to any other either in terms of truth value or contribution to human flourishing. Islam is not worse that Christianity or Buddhism; it is just different, and only a bigot thinks otherwise.
But of course most leftists think that all religions are bad, equally bad. But if so, then again one cannot maintain that one is superior or inferior to another.
8. Leftists tend to be moral equivalentists. And so we witness the amazing spectacle of leftists who maintain that Christianity is just as much, or a worse, source of terrorism as Islam. See Juan Cole, Terrorism, and Leftist Moral Equivalency.
Leftists are also, many of them, moral relativists, though inconsistently so. They think that it is morally wrong (absolutely!) to criticize or condemn the practices of another culture (stoning of adulterers, e.g.) because each culture has its own morality that is valid for it and thus only relatively valid. The incoherence of this ought to be obvious. If morality is relative, then we in our culture have all the justification we need and could have to condemn and indeed suppress and eliminate the barbaric practices of radical Muslims.
9. Leftists tend to deny reality. The reality of terrorism and its source is there for all to see: not all Muslims are terrorists, but almost all terrorists at the present time are Muslims. Deny that, and you deny reality. But why do leftists deny reality?
A good part of the answer is that they deny it because reality does not fit their scheme. Leftists confuse the world with their view of the world. In their view of the world, people are all equal and religions are all equal -- equally good or equally bad depending on the stripe of the leftist. They want it to be that way and so they fool themselves into thinking that it is that way. Moral equivalency reigns. If you point out that Muhammad Atta was an Islamic terrorist, they shoot back that Timothy McVeigh was a Christian terrorist -- willfully ignoring the crucial difference that the murderous actions of the former derive from Islamic/Islamist doctrine whereas the actions of the latter do not derive from Christian doctrine.
And then these leftists like Juan Cole compound their willful ignorance of reality by denouncing those who speak the truth as 'Islamophobes.' That would have been like hurling the epithet 'Naziphobe' at a person who, in 1938, warned of the National Socialist threat to civilized values. "You, sir, are suffering from a phobia, an irrational fear; you need treatment, not refutation."
When a leftist hurls the 'Islamophobe!' epithet that is his way of evading rational discussion by reducing his interlocutor to someone subrational, someone suffering from cognitive dysfunction. Now how liberal and tolerant and respectful of persons is that?
10. Leftists hate conservatives because of the collapse of the USSR and the failure of communism; hence they reflexively oppose anything conservatives promote or maintain. (This was Peter Lupu's suggestion.) So when conservatives sound the alarm, leftists go into knee-jerk oppositional mode. They willfully enter into a delusional state wherein they think, e.g., that the threat of Christian theocracy is real and imminent, but that there is nothing to fear from Islamic theocracy.
11. Many leftists are cowards. They will not admit the threat of radical Islam or speak out against it because of fear of reprisal. It is a rational fear, of course. And so the very same people who accuse conservatives of an irrational fear of radical Islam stick up for it out of a quite rational fear of what would happen to them if they condemned it the way they would condemn Christian terrorism if such a thing existed.
12. Leftists are fundamentally negative and oppositional. In Faust, Goethe refers to Mephistopheles as Der Geist der stets verneint, the spirit that always negates. That is the spirit of the Left: destructive, nay-saying, reactionary. So leftists take the side of Islamists because the latter oppose traditional American values despite the deadly threat Islamists pose to their own values. Compare Robert Tracinski:
The left is fundamentally reactionary. It is a reaction against capitalism and against America. The left are defined by what they are against, or more accurately who they hate. So they are drawn to sympathy toward Islam because it is not-us: non-Western, non-American, neither Christian nor a product of the Enlightenment. And I guess that’s what the two ideologies have in common: they are both reactions against the supposed evils of the West. Which explains why leftists tend to find themselves uncomfortable and look for excuses to retreat when they are called upon to defend the West against this rival group of reactionaries.