At the end of this post I suggested there might be a paradox in liberalism's claiming moral validity for the framework it lays down for the public life of pluralist democratic societies, while denying the claims of other belief systems to have identified a single 'road to salvation' or an 'overriding moral truth'. Ophelia at Butterflies and Wheels proposes a resolution of the paradox, if it is one, by arguing that 'road to salvation' and 'overriding moral truth' are not the same sort of thing as 'pluralist liberalism'. In many respects they're not, and some of these Ophelia identifies - like openness to discussion and the absence of it, for example.
Still, I think she's missed the point of my question or, what comes to the same thing, the paradox I had in mind: that, like adherents of a single 'road to salvation' or an 'overriding moral truth', adherents of a liberal moral and political framework do also claim a moral primacy - universal validity, whatever - for some of their own beliefs: for the very principles informing that liberal framework. The fact that there are relevant differences between liberalism and such other, non-liberal, belief systems - differences that Ophelia and I will agree are in liberalism's favour - doesn't show that there isn't this feature in common between them, or resolve the particular tension I was suggesting.