To coincide with the new book he co-edited on this topic, Eduardo Mendieta discusses Habermas and religion.

The centrality of religion to social theory in general and philosophy in particular explains why Jürgen Habermas has dealt with it, in both substantive and creative ways, in all of his work. Indeed, religion can be used as a lens through which to glimpse both the coherence and the transformation of his distinctive theories of social development and his rethinking of the philosophy of reason as a theory of social rationalization.

Find it here; details on the book itself here. [update 20th Feb 2011 – the book is now out, details here]