I'm not sure how far Derrida's later 'theological' interests are really rooted in post-structuralism or whether they don't rather reflect a kind of Kantian-Marxist trajectory - with a French twist on the centrality of liberty, equality and fraternity (cf. Politics of Friendship). Not to mention the role of Levinas and, behind Levinas, Judaism's twinning of eschatology and the call for justice.

And this is also what he takes Christian doctrine, in all its complexity, to be centrally about, that is, teaching an attitude rather than a set of propositions. Call it joyous openness to life. What's not relevant about that?

And one thing the void certainly can teach us is how to wait, how to become truly patient, and how to let go of superfluous intellectual baggage - all of which is a good lesson for hyper-agitated multi-tasking goal-focussed contemporary human beings.

Religious life is about something real in human experience that is not constrained by what Wittgenstein called 'all that is the case'. In this sense Heidegger is not simply 'mistaken' - he just asks us, as philosophers mostly do, to think more carefully about what we're saying.

When I'm on the operating table, I'm happy for the surgeon to treat me as a machine, but the moment I return to consciousness I have other needs and aspirations that should be recognized. We're not here only to survive or extend our individual or species life but to do something seemingly more difficult, for which I've used words and phrases like 'love' and the 'Kingdom of God'.

But why should a religious person be interested in a work like Heidegger's that many regard as the epitome of nihilism? For a start, because Heidegger forces us in a way that few philosophers do to really think through the seriousness and all-encompassing nature of our mortality.

And perhaps this has to do with what I sense is a turning away from the idea of religion as being about conserving a certain heritage from the past towards religion as having to do with how we orientate ourselves to the future, to all we truly long for, to hope.