Then there is Stephen Fry. A decade ago, when the Millennium Dome opened, he was one of the main stand-up acts. In front of a crowd of families and people of all ages, he joked: "Good evening ladies, stroke gentlemen, stroke girls and, of course, stroke boys." 

This does not mean that Fry approves of paedophilia. He is simply happy to get a laugh out of it when it suits him. And this is what our new celebrity preaching class can do: make a pronouncement on politics and if you catch them out, remind you that they are not politicians; make claims about history yet they are not historians; make claims about ethics yet not be interested in ethics. 

Clerical classes have existed in all societies. But the version Britain has started to rely on must be the first that not only doesn't expect to hold itself to account, but isn't expected to by anyone else to do so either.

And these people are important not just because of what they say, but because 

 they are what so many young people seek to become. The Pope acknowledged this, asking a young audience to think about celebrity culture and consider whether that was what they would truly like to become.

At the heart of modern Britain is a terrible sickness: nihilism. The Church of England has left a void in the public square. And in this situation, Pope Benedict's visit constituted a striking achievement: he put Christianity, for the first time in many years, firmly back into the centre of the debate in our national life. 

You do not have to agree with the Pope to recognise the force and significance of his arguments. But it would strike me as unwise to pretend that his arguments have no merit simply because they are uttered by a Pope.

As the late Oriana Fallaci said: "If an atheist and a Pope think the same things, there must be something true."