Foundation stone

I've just come across this quote from Jürgen Habermas, but can find little about what he says to back it up.

Christianity, and nothing else, is the ultimate foundation of liberty, conscience, human rights, and democracy, the benchmarks of Western civilization. To this day, we have no other options [than Christianity]. We continue to nourish ourselves from this source. Everything else is postmodern chatter.

It interests me because this notion has been with me for some time, but I do not know enough to delve any deeper. Put crudely, the concern is this: on fundamental questions such as the equal value of each individual, which derives from the Judeo-Christian vision of the immortal soul, will it be enough for a secular society to assert their truth in law? Or will that position be gradually and irretrievable undermined by technology? Lacking a metaphysical or transcendent anchor, will a secular society merely be able to reflect what can be done rather than impose what should be done?

I found another statement of Habermas's views here at Aimee Milburn's blog. She quotes Virgil Nemoianu, Professor of Literature and Philosophy at Catholic University of America, who has examined the transcripts of the Habermas-Ratzinger debate in 2004.

From the very beginning . . . Habermas admits the legitimacy of the question as to whether the secularized and rights-founded state is not nourished from normative premises that are alien to its own nature and antedate it. “This would raise some doubts as to the ability of the constitutional democratic state to renew its existential foundations from its own resources, rather than from philosophical and religious, or at least from a general ethical communal prior understanding.”