On Religion, Soho Theatre, London <!-- none onestar twostar threestar fourstar fivestar -->

In Monday's Independent, Richard Dawkins railed against parents foisting their religion onto their children, calling it a form of child abuse. In On Religion, we are presented with the intriguing premise of a female Dawkins figure whose son announces his intention to join the priesthood. Is her refusal to accept his actions similarly abusive?

Following last year's On Ego, Mick Gordon has teamed up with the philosopher and atheist AC Grayling for a "theatre essay" on the burning topic of the day. Based on testimonials from, among others, the Muslim academic Tariq Ramadan, Archbishop Rowan Williams and, of course, Dawkins, On Religion plays out the science vs religion debate through the microcosm of one family.

At the head of this family is Grace, a passionate academic with the voice of Dawkins, the product of a violent Catholic upbringing and so committed an atheist that she refuses to acknowledge the term, preferring "naturalist". When we meet her she is the guinea pig in an experiment to see if a religious experience can be replicated by science using specially placed electrodes in a "God helmet".

Then there is Tom, her equally passionate son who gives up his legal career to become a priest - an act that Grace initially dismisses as a form of late-flowering teenage rebellion but which eventually tests the mother-son relationship to its limits. On the periphery are Tony (Pip Donaghy), husband, father and a non-observant Jew - a genial fellow who greets news of his son's new career with "Oy vey!" - and Ruth, Tom's pregnant girlfriend, an atheist dealing with the aftermath of her mother's suicide.

The scene is ripe for some interesting arguments that mingle the personal with wider concerns: should you marry a priest if you don't believe in God? Is Grace the fundamentalist of whom we should be most afraid? Should the world be divided into the haves and have-nots of belief? It all ticks along at a good pace, and the clever, if slightly tortuous, structure creates dramatic momentum.

There's one major flaw, though - the four main characters, or mouthpieces, are all very difficult to warm to. Their intellectual banter over breakfast grates - how fondly they remember the hilarious childhood prank when Tom added a crushed-up ecstasy tablet to his father's chicken korma - as do some truly toe-curling scenes involving silly dancing.

Grace (a sparky Gemma Jones) is rabidly self-obsessed, so her struggle to reconcile motherhood with her own beliefs is less than convincing, and although Tom has many of the most persuasive arguments - he and the play warn against dogmatic thought or belief of any kind - Elliot Levey delivers his lines with a patronising oratory style borrowed directly from Tony Blair.

I had the distinct feeling of being back in the lecture hall more than once. Grayling and Gordon need a little more theatre and a little less essay.

To 6 January (08704 296 883)