Pluralism is an aspect of a tolerant morality. Not the morality itself. And the only way that a functional society, based on said morality, will take root is if the culture freely embraces it. I'm not particularly sure why you think you can divorce the mindset of the people from the central authority and its applied governance (i.e. the "official" decisions that accept or reject a given mindset) when they all compose the same culture.
The only really notably cultural disconnect you can pull out of a hat is the French Revolt and its ensuing bloodbath. But even then, the vast vast VAST majority of French were Catholic just the same as the Royal Family, and it was Hugenot upper classes that socially engineered the peasants into a festival of anti-religious violence. In which case, the subsequent establishment of secularist laws and the Authoritarian-sourced Napoleonic Wars that followed hindered France's cultural development rather than improved it.
Why exactly do people with a dislike for theism tend to think that society can achieve social equanimity without an applied Manichean philosophy? There is no basis for a set of ethics and morals if you do not strictly define "right" and "wrong". It's always mystified me how one can come to the conclusion that cooperation (as opposed to consolidation) is somehow the natural order of things despite having an array of wildly different, utterly incompatible moralities trying--and failing--to intermix. The idea that Christendom's Manichean structure made no real contributions to modern commerce and society beyond an introduction of dogmatic mysticism is childish at best and ignorantly prejudicial at worst.
The concept of free will is totally unique to Judeo-Christianity, and is the only real source of tolerance and pluralism in the West--which is exactly why I took issue with the way you tried to make it somehow indistinct from Islam.
Despite my antipathy for Luther, Calvin, et al. The Protestant Reformation was not a rejection of spiritualism. Their primary issue was the precedence behind Papal authority with respect to heavenly edicts. They still believed in a free will, providence, and divine arbitration. Darwin's contributions, for that matter, consisted of adding another story to the long condemned structure known as "Marxism" and only served to aid Lenin, Stalin, and Hitler in validating their respective, and religiously secular, campaigns for dominance.
Now I remember why I don't come to this board. I always come away feeling like I have stepped in incorporeal dog shit and spend the next hour trying to wipe it off my psyche.
Is this frustration motivated by my (admittedly) persnickety tone or simply because you disagree with what I'm saying?
If it's the former, I already pointed out why your post felt more than a little backhanded, so I wouldn't say it's unprovoked. If it's the latter, might I suggest applying some thicker skin? I think you take for granted the idea that there are certain things with which everyone's going to agree on solely humanitarian grounds.
On that note: I fail to see what your link proves about Islam itself. What kind of intellectual point is being made with regards to the philosophy of Islam by emphasizing the opinions of people within it rather than the philosophy itself?
Indeed, our once local philosophy collegiate, Animalman, tried to go the "it's all a matter of interpretation" route and express that anyone can intuit what they like from the Q'uran, Bible, etc. and aptly deconstruct it into constituent parts without any concern for its message as a whole. But his dislike and disregard for Ontological Empiricism is his own imperfection. And I don't recommend that you adopt it.