By intermission, it’s fascinatingly unclear where Drew Pautz’s bitter comedy of religious and sexual politics “Love the Sinner” is heading. The first act whips tension up to a pitch that whets the appetite for further well-nigh absurd debate and potentially wrenching personal drama. If it doesn’t finally deliver on that dual promise, the quality of writing and performance keeps audiences tense for most of the journey.

Pautz plunges headfirst into the diplomatic minefield of a negotiating table at a religious affairs conference in an unnamed African state. Given that the chief agenda item is attitudes to acceptance of homosexuality, it’s unsurprising that surface politeness is cracked open.

Not only is Pautz’s handling of the arguments around post-colonial cultural differences and sexuality unexpectedly funny — he’s as interested in the speakers’ game-playing as what they are actually saying — but the entire scene wrong-foots everyone. What looks like an issue-based debate play is swiftly revealed to be nothing of the sort.

Because the characters are supposed to be sequestered, they only agree to coffee being brought in so long as they don’t communicate with the waiter Joseph (a piercing debut from Fiston Barek). The sequence in which he serves and observes a group of leaders with their eyes tightly shut is deliciously comic. But it also sets the scene for more personal confrontations.

Coffee has been ordered by Michael (Jonathan Cullen). He’s the conference’s layman note-taker who, in the brilliantly suggestive, thrillingly tense scene that follows, is discovered post-coital in his hotel room with Joseph. It’s life-changing for married Michael, but not in a good way.

This superbly acted scene is as tense and frightening as Pinter’s “Betrayal.” Pautz rivets attention to every unspoken thought. Mutual suspicion curdles into dangerous threats as the two differently manipulative men battle for control. Joseph turns belligerent — he wants to go to England — while white Michael tears himself apart with regret and liberal guilt over his treatment of the young black man.

Back home, Michael hides the truth from his wife, Shelly (fiercely clear Charlotte Randle), who yearns for a child and is suspicious of her husband’s reticence and his retreat into religion. “You’re sweating,” she cries accusingly. “If you’re not sweating, you’re praying.”

The second act’s mirroring of the first points to structural command — Pautz, a Canadian writer, is making his National Theater debut with only his second play — but his use of dramatic metaphor slides into self-consciousness. The plot develops via confrontations of tersely expressed anguish (a gift for actors) but scenes lack developed action and characters ultimately wilt under the strain of embodying positions.

But Matthew Dunster’s direction examines every beat of the script and he elicits an outstanding lead performance from Cullen. His character is awash with terrified indecision, but Cullen makes every fraught change of thought instantly legible without ever holding a scene to ransom.

Anna Fleischle’s design creates varied spaces but despite being made chiefly of wood, the space feels unhelpfully chilly.

“Love the Sinner” is as much about denial and responsibility as it is about the contradictions of contemporary Christianity. Less than the sum of intriguing parts, its passages of truly dramatic writing highlight Pautz as a talent on the rise.

Love the Sinner

National Theater, Cottesloe, London; 306 seats; £32 top

  • Production: A National Theater presentation of a play in two acts by Drew Pautz. Directed by Matthew Dunster.
  • Crew: Sets and costumes, Anna Fleischle; lighting, Philip Gladwell; sound, Paul Arditti; music, Jules Maxwell; production stage manager, Xenia Lewis. Opened, reviewed May 11, 2010. Running time: 2 HOURS, 20 MIN
  • Cast: Michael - Jonathan Cullen Joseph - Fiston Barek Shelly - Charlotte Randle John, Rev Farley - Paul Bentall Hannah, Alison - Nancy Crane Tom, Bill - Sam Graham Matthew, Harry - Robert Gwilym Daniel - Scott Handy James, Dave - Fraser James Paul - Louis Mahoney Stephen - Ian Redford Simon, Official - Richard Rees
  • Music By: