The Mikvah Project, The Yard, Hackney

In the beginning was the Word and, not long after, came a need for ritual purification. “When Adam was banished from Eden, he sat in the river that flowed from the garden. Adam immersed in the water, in the very first Mikvah …”.

Goyim audience members will be grateful, as I was, for the gloss on this traditional Jewish practice given by one of the characters in the opening minutes of The Mikvah Project, the first full-length play by Josh Azouz, who is currently on the Royal Court’s writers programme. We were more grateful still for his bringing the ballast of comedy to such topics as faith, transgression and unsanctioned love. Without the laughter that ripples though this piece, its weighty cargo might well have sunk.

Avi, 35, and Eitan, 17, cross paths every Friday night at a north London Mikvah, startlingly realised on stage with a full-sized, water-filled pool (design, Cécile Trémolières). The pair have little in common beyond synagogue and a love of football. In fact the older, married man (played with glittering intensity by Jonah Russell, fresh from the Young Vic’s A View from the Bridge) at first finds the callow Eitan (a rubberball Oliver Coopersmith) irritating at almost every level. “Why do Jewish boys from Finchley insist on talking as if they come from Jamaica?” he snipes. Eitan, for his part, is half sceptical, half in awe of Avi’s religious zeal. Why, he asks, does he immerse himself nine times when tradition demands only three? The answer: so that his sperm “can become better swimmers”. Avi is still childless after eight years of marriage, and his relationship is feeling the strain.

Jay Miller’s direction, another sure-handed debut, makes light work of the many rapid third-person monologues, delivered at microphone stands, and live incidental music, begun as a hummed line of melody and embellished, sometimes to glorious choral effect, by electronic looping. The men’s nakedness feels unforced, too. In fact it’s a measure of the characters’ credibility that it would have been embarrassing if the actors hadn’t stripped off for immersion.

Little by little, we learn things about Eitan and Avi that modify our initial assessment, not just of them and their relation to each other, but also of secondary characters who don’t appear. And, given the claustrophobic setting (the characters can only be in the pool, or out of it), the writer succeeds in creating some impressive mood changes and narrative swerves. Suffice to say that Eitan and Avi’s story is not predictable at any point.

I loved this play, for its frankness, its honest physicality, its two superlative, under-the-skin performances, and its sense of fun. To judge by his online profile, the playwright has devoted many of his earlier theatrical efforts to intercultural understanding, particularly between Jews and Muslims. If we truly wish to respect faith through knowledge and insight, The Mikvah Project is a good place to start.

• The Mikvah Project at the Yard Theatre, Hackney, through 14 March