Security has been stepped up in Jewish communities around the world following the recent terrorist attacks in Paris, but in Joshua Harmon's fiercely funny play Bad Jews, which centres around a grieving Jewish family, it is themselves they need protection from.

Daphna (Jenna Augen) and Jonah (Joe Coen) are cousins, but that's about all they have in common. Daphna, in town for the funeral of her Grandfather - or Papi - is a 'Super Jew' who complains about interfaith marriage, has an Israeli boyfriend named Gilad and dreams of moving to Israel and joining the army once she has finished university. Confrontational and cocksure, she is the kind of person you don't ever want to be in an argument with.

Jonah, on the other hand, is a champion fence-sitter, content with playing Xbox in his New York apartment with views over the Hudson paid for by his parents. Conversation between the two is mostly one way, with Jonah's attention more on his console than his cousin. It's a slow start, but that soon changes when Jonah's brother Liam (Ilan Goodman), returns from a skiing trip, having missed Papi's funeral, with girlfriend Melody (Gina Bramhill) - a vacuous yet well meaning shiksa with Barbie blonde hair - in tow.

Round One. The pair take turns ripping each other apart, deconstructing each other's perceived Jewish identity, before Daphna turns on Melody, passive-aggressively ridiculing her very being in the name of self-affirmation. The knockout round comes when the fate of Papi's chai, a cherished family heirloom from the Holocaust, is discussed. Daphna thinks her spiritual and cultural attachment to the medallion makes her the rightful owner; Liam disagrees and Jonah apparently doesn't care.

Harmon's brutal script is superbly delivered by the cast of four. Augen's performance is a real tour de force and it's not hard to see why she won the UK Theatre Award for the play's initial run at the Ustinov Studio, Bath last year. Goodman proves a worthy opponent as Augen's foil and self proclaimed 'Bad Jew', matching her for energy output alone is a feat in itself. Both are wonderfully supported by the hilarious Bramhill and subtle Coen, Michael Longhurst's direction ensuring a speedy pace throughout the piece which runs at 1 hour 40 minutes straight through.

If I have any reservations about this production, it's that Daphna is such a despicable character, an opinionated, self-obsessed egomaniac who lacks the ability to empathise with anyone who doesn't share her beliefs. So much so that by the time Liam arrives, about 30 minutes into the play, and exclaims "she's such a f*****g c**t", you can't help but agree. The result is that any argument or justification she attempts to make, no matter how valid, falls by the wayside. You don't want her to win from the start and so the battle is won before it has started.

Bad Jews is a ferocious play about identity, within families and religions. It grabs you by the balls and has you laughing as much as wincing for the duration. If you can handle a non-stop verbal onslaught which includes two c-bombs, then get yourself down to the St James Theatre.

Bad Jews runs at the St James Theatre until 28 February. Click here for more information and to buy tickets