The dialogue between Joseph Ratzinger (Pope Benedict XVI) and Jürgen Habermas:
[Zur debatte, 1/2004, free access]
"I assume that the constitution of the liberal state can satisfy its need from legitimation in a modest way by drawing on the cognitive resources of a set of arguments that are independent of religious or metaphysical traditions." (....) "...the proceduralist conception of Kantian inspiration insists on an autonomous grounding of constitutional principles that claims to be rationally acceptable to all citizens."
The liberal state is not incapable of "reproducing the motivations on which it depends from its own secular resources."
"(....) the secular character of the constitutional state does not exhibit any internal weakness inherent in the political system as such that jeopardizes its ability to stabilize itself in a cognitive or motivational sense. This does not exclude external reasons. An uncontrolled modernization of society as a whole could certainly corrode democratic bonds and undermine the form of solidarity on which the democratic state depends even though it cannot enforce it. (....) Evidence of such a corrosion of civic solidarity can be found in the larger context of the politically uncontrolled dynamics of the global economy and global society."
(English translation in Jürgen Habermas, Between Naturalism and Religion (Polity, 2008), pp. 101-113.