Love the Sinner, National Theatre: Cottesloe, London

This new play by Canadian dramatist Drew Pautz is topical, tender-hearted, fascinating and flawed. At times, it gives the impression of drifting out of focus, but that is because it is so alert to the ramifying consequences and intractability of the problems it tackles. It says a lot for Matthew Dunster's production that you remain anxious, throughout, to know what will happen next.

The piece opens in an unspecified African country at an international conference of Anglican bishops struggling to reach some semblance of consensus on the near-mortally divisive issue of homosexuality. With an even-handed wit, Pautz declines to score easy points off Paul, the illiberal African bishop (a compelling Louis Mahoney). This latter argues that upstart, morally shallow Christian sects are seducing his local flock from the Anglican communion. The main character is Michael (hauntingly well-played by Jonathan Cullen), a married businessman from England, who has volunteered to take the minutes. He's also a closet gay and in the play's best scene, the aftermath of a sexual fling with Joseph, the African hotel porter, turns into a nightmare. Joseph (Fiston Barek) fiercely and flightily threatens to blackmail him into taking him home to English asylum.

A lesser dramatist would have made Michael a thoroughgoing hypocrite and Joseph a pure victim of Western double-standards. But, as the play – and Joseph – pursue him back to England and his fraught marriage with Shelly (an unnerving Charlotte Randle), we see, in Michael, a man who is striving to be good and for whom evangelical Christianity functions as a kind of lifebelt. If the performance by Barek (making his debut) were not so dazzlingly persuasive, one might well feel that the character was too much a device for highlighting divisions within the Church. There are patches of implausibility, but this thoughtfully provocative play gets my secular blessing.

In rep to 10 July (020 7452 3000)