Until last week, I hadn't believed in ghosts; now I'm not so sure. Maybe it was drinking champagne in a crypt, perhaps the conjuring-up of things I had vaguely thought of as dead: the Church of England, Margaret Thatcher, figurative painting. There's nothing like toping with shades to make you believe in them.

There they all were: the Dean of St Paul's in black cloth and dipthongs; Mrs Thatcher - Baroness Thatcher - spectrally bouffant and wrapped in sable; and Sergei Chepik, a spectacled Russian bear whose four paintings - The Nativity, Public Ministry, Crucifixion and Resurrection - we had come to St Paul's to toast. Or, this being a church, to dedicate.

How do you dedicate art? It seems like this. You leave your champagne down with the dead and sit on a chair under a dome. You try to look as though you aren't sneaking glances at Lady Thatcher, who has a fine pair of pins but really shouldn't wear purple. You listen to minute choristers, up past their bedtime, singing "When I survey the wond'rous Cross". You stare as a priest, all optimism and syrup, describes Chepik's pictures as "absolutely of their time".

And you wonder whether someone has spiked your Krug. Last February, St Paul's hosted a show of work by, among others, Billy Childish and Tracey Emin. On Shrove Tuesday, an actor dressed as Christ walked through the City in a piece called Iconography, part of the same show. Could this dedication be performance art as well? Some Fellini-ish satire on a doomed bourgeoisie, with look-alike deans and peeresses and champagne for Communion wine?

It seems not. Startled by the attendance figures for Tracey and Billy, the Church has hit on the fact that art is cool; that more worship goes on over the river at Tate Modern than does in St Paul's. And so they have cast about for modernity, for artistic relevance, and have found Chepik; a man who painted Ivan the Terrible, gargoyles and Lady Thatcher, who drew his inspiration from the gulags. They have commissioned him to bring St Paul's up to date and, in a way, that is what he has done.

The date, though, is 1989, when Reagan was in the White House, the Berlin Wall still stood and the Daily Telegraph, scenting tradition, was declaring Sergei Chepik "an unknown Russian genius come to light".

Mrs Thatcher congratulated Chepik in the Commons; then Wall came down, she was ditched and Reagan left office. And now, two decades on, the unknown Russian genius has hung his work in St Paul's, uniquely qualified to do so by history.

Really? I don't want to be unkind, but Chepik's paintings are dire: like flip-boards for a Mel Gibson Christ-a-thon, all comic book torture and schlock. Even his story - the triumph of free enterprise over totalitarianism - seems passe now, overtaken by Rwanda and al-Qa'ida and Banda Aceh. If suffering allows you to know The Passion, then hundreds of other artists are better qualified.

So why has the Church chosen Chepik? I can't say. The praying done, we wandered across Wren's nave to a side chapel, and then to another bar with more champagne; which was where I found myself, unusually, wondering where I was, and why.