Theatre Son of Man RSC The Pit, London

'Potter's Christ comes across as a Sixties liberal ahead of his time - preaching a simplified gospel of peace, love and social equity'

When Son of Man, Dennis Potter's play about the life of Jesus, was first broadcast on television in 1969, Mary Whitehouse wanted to have Potter prosecuted for blasphemy. Seeing it on stage at the Pit, you wonder quite what the problem is; because while Bill Bryden's production for the RSC is finally a disturbing and thrilling piece of theatre, Potter's script often feels as though it's hobbled by too much reverence.

The play's aim is, as the title implies, to show Jesus as fully human, which implies putting him into his social, political and professional context (there's quite a lot of carpentry in the production) - so we get John the Baptist as an anti-Roman agitator, a Pontius Pilate worried by the political implications of Christ's message, Jewish priests nervously trying to maintain the status quo. The problem is that while Potter wants to dodge the issue of Christ's divinity - there's a carefully weighed ambiguity on that score throughout the piece - he's still enough of a child of the Chapel to need to feel that Jesus's message is still relevant to us today. But if you really tried to portray Him realistically as a first-century Messianic preacher, you would end up with a Jesus whose ways of thinking are largely incomprehensible and even unpalatable to a modern audience.

So Potter's Christ comes across as a Sixties liberal ahead of his time - preaching (often in language fatally reminiscent of the Alternative Rocky Horror Service Book) a simplified gospel of peace, love and social equity that's likeable enough, but hardly the basis of a major world religion. Even the hostile Roman reaction to Jesus is couched in terms agreeable to left-wing intellectuals - Pontius Pilate (an excellent John Standing) insisting to his bellicose military commanders that "Ideas are what we fear." The sense of compromise is the play's major weakness - along with the fact that it runs nearly two and a half hours without a break, in seats designed with the stumpier theatre-goer in mind.

But while Potter's script is not among his best, he's still working with what's commonly held to be the greatest story ever told, and there are good things: Jesus casting a carpenter's eye over the timber of a cross; the way that he shifts from a refusal to acknowledge his divinity to a demand that people praise him.

Bryden's staging, while unevenly cast and at times annoyingly folksy, does bring out the latent power of the narrative. It's especially impressive at the beginning - which places the action in a Gloucestershire carpenters' workshop, with the carpenters singing a rousing hymn before hammering together a stage for the action to take place - and at the end: there is a marvellously held silence when Joseph Fiennes's charismatic Jesus appears before the high priest; and the Passion itself is harrowingly staged (though it might be even more powerful without a Dire Straits-style guitar solo).

There are, in the end, many things wrong with Son of Man; and though it triumphs, it's hard to pick out what, apart from the storyline, keeps it afloat. Perhaps we should settle for saying that it moves in a mysterious way.

n To 13 January. Booking: 0171-638 8891