Lindbeck's The Nature of Doctrine

I have been slowly making my way through George Lindbeck's landmark book The Nature of Doctrine. In short, he argues that Christian doctrines are in fact regulative rather than propositional: that is, they are not chiefly first-order propositions with ontological reference but rather second-order rules of speech. They are agreements to speak in a certain way. They are paradigms for thinking and talking, mostly. He says of the creeds:

Rule theory...allows (though it does not require) giving these creeds the status that the major Christian traditions have attributed to them, but with the understanding that they are permanently authoritative paradigms, nor formulas to be slavishly repeated.

Fair enough.

It is striking that the beginning of his discussion is a concern to mediate between different types of Christian theologies. He begins in the ecumenical setting - so his whole purpose is to find a way of classifying statements made in that setting. It is, it seems to me, a Study of Religions kind of work. So I am puzzled about its influence on theological work, somewhat. He has relativised the doctrinal differences between Christian traditions...because different statements might fit authentically within different traditions and not others...