Martyr (Unicorn Theatre)

"I have a normal boy with behavioural problems," says the mother of a Bible-spouting weirdo, Benjamin Sinclair (new RADA graduate Daniel O'Keefe), who objects to his black girlfriend swimming with Christians and disrupts a sex education class with carrots and condoms by stripping stark naked and denouncing the biology teacher ("Do carrots make you pregnant?… My penis is not a vegetable").

It's hard to take Marius von Mayenburg's 2012 German play (translated by Maja Zade) too seriously as Ramin Gray's production for the Actors Touring Company operates on a scattergun critique of fundamentalist fanaticism without much psychological analysis. The writing is more emblematic than penetrating, not necessarily a bad thing, though a more severe production would serve it better.

Ben's biggest problem – apart from wanting to die for his faith – is his problem with women. The young girls in the first night audience simply sniggered and gasped. He won't allow the girlfriend (Jessye Romeo) to touch him, he rails against mum (Flaminia Cinque) for being divorced, he "can't bear to look at" the biology teacher (Natalie Radmall-Quirke) because "she's a Jew."

All of this bilious rubbish is conveyed in bleeding chunks of the King James bible taken out of context and at face value, which is quite a good way, as it happens, of suggesting the lunacy of a blinkered, mixed-up zealot.

'An awkward, uncomfortable 95 minutes '

The show highlights Ben's nastiness, too, by making the biology teacher, in fact, a warm-hearted, sympathetic Irish woman, and the headmaster (Mark Lockyer on bizarrely eccentric form), a more cheerfully ludicrous character (with sudden shafts of sexist bullying) even than the pupils he disciplines; though Sinclair's Ben does have the chilling, switched-off demeanour of a dangerous skinhead who kept reminding me of the Oklahoma bomber Timothy McVeigh.

We start with a christening and end with a crucifixion: Ben dives in a little plunge pool and the martyr (not the person you expect) nails a pair of feet to the floor, and blood trickles down the plywood slope. Both these scenes are somewhat timidly staged, probably because of the constrictions of a touring set (designed by the director) which also keeps the actors on stage throughout and the headmaster strumming a guitar in his office.

Things get a little more interesting and complicated with Ben's diffident friendship with a crippled acolyte, George (Farshid Rokey), though this development – despite a laying on of hands and a weird notion that Ben's fruitcake frothing is evidence of miraculous powers – is so sudden you wonder where it came from; and of course the same sex smack of lips prompts the usual yucky squirming and squealing among the teenagers in the audience.

I imagine that von Mayenburg's original production at the Schaubühne in Berlin was far more Teutonic – a sort of extreme Spring Awakening with sharply satirical edges and a fearsomely realistic design – and that might have been even more upsetting than this version. Martyrmakes for an awkward, uncomfortable 95 minutes without wrestling the horrors of bovine bigotry to the ground.

Martyr continues at the Unicorn until 10 October