Andrew – I look at these sorts of things from a slightly different perspective. I try to look at any political vision which attempts to redefine the fabric of society as de facto religious. It doesn’t always work, but it does quite often and is always very illuminating. The beauty of classical liberalism — like modern libertarianism and, I would argue, political conservatism properly understood — is that it is a partial philosophy of life. It has no answer for how men may pursue happiness, only that they should be free to do so within some reasonable guidelines, most of which stem from the prohibition of harming others.*
Much of what we see in multiculturalism and environmentalism is an attempt to beat back one religious worldview to make room for another. The brilliance of the left is that they simply don’t call identity politics and nature worship “religions.” I am opposed to Christians trying to force all of society to adhere to their tenets (though I see much less of this actually happening than certain hysterics do and I grow much more tolerant of such things as the principles of local autonomy kick in). But I am also opposed to nominally secular forces trying to do the same thing. It seems to me that a movement shouldn’t be given free reign to tell people how to live and impose their vision on society simply because they don’t invoke religious authority. Enforced Gay Pride month in government buildings — whatever the merits of gay pride may be — is no less offensive to me than Christian Pride Month would be. But Christian Pride is banned. Gay Pride is well-funded.
I should also note that our constitution actually gives very wide berth to religious freedom. So while your discussion with David Frum about England is an exception, when you write that “once a democracy has put those laws in place, I can think of no particular reason why some people should be exempted from that law,” you run into the problem of the US Constitution which guarantees the free-exercise of religion in the Bill of Rights. And, as you surely know, the whole reason we have a bill of rights is to protect us from democratic laws which are unjust and illiberal despite being supported by the majority.
* This is not to say that conservatives don’t have a lot of good suggestions on this front. And, in fairness, conservatives and libertarians surely disagree on where the lines are drawn in this sort of thing. But you get my point.