“It is an ethical obligation to look for hope; it is an ethical obligation not to despair.”

As spoken by the playwright Tony Kushner in a friendly, reasonable voice in “Wrestling With Angels,” Freida Lee Mock's admiring documentary portrait of Mr. Kushner, those words sound like basic common sense. If we want a better world, we'd better be able to imagine it.

 
Mr. Kushner has the imagination as well as the gumption
to put his body where his words are. A brief scene near the
end of the film shows him in Miami on the day of the 2004 presidential election helping people vote after being turned away from their polling place.

 
Throughout the film his easygoing buoyancy contradicts
the clichéd image of the left-wing intellectual as a grim,
preachy commissar of political correctness. He is a welcoming public figure who has a gift for being very funny and serious at the same time. Whatever his subject, his words are usually accompanied by a playfully disarming grin. As much as he knows about history, literature and Jewish culture, he never pontificates like an academic know-it-all.

 
How we live in the world, Mr. Kushner says, depends on
our willingness to empathize with others. And empathy seems to come naturally to this gay, Jewish playwright, now 50, who was born in New York, grew up in Lake Charles, La., studied medieval history at Columbia, and won a Pulitzer
Prize for “Angels in America,” his epic play about AIDS in the Reagan era.

 
As informative as it is, “Wrestling With Angels” doesn't have time to do more than scratch the surface of its fascinating subject. If you haven't seen “Angels in America,” the snippets excerpted from the Mike
Nichols-directed HBO movie of this visionary work barely hint at its substance. Mr. Kushner mentions his admiration for Brecht's epic theater, which inspired his first play, “A Bright Room Called Day,” but not at enough length to establish a deep connection.

 
The excerpts from the autobiographical musical “Caroline,
or Change,” his collaboration with the composer Jeanine Tesori, are more resonant, because that work's story of a Jewish boy’s embattled relationship with his family's black housekeeper in Louisiana is more contained. Ms. Tesori describes Mr. Kushner as a song lyricist who “uses language as the driving rhythm.”

 
“Wrestling With Angels,” which opens today at Film Forum in New York, is thematically structured as a three-act play, with each act given its own portentous title. Act I, “As a Citizen of the World,” concentrates on Mr. Kushner's
interest in global issues and discusses his play “Homebody/Kabul,” about Afghanistan, a historically prescient work that he began writing well before the American invasion in 2001.

 
Act II, “Mama, I’m a Homosexual Mama,” focuses on his
involvement in the gay-rights movement and AIDS crisis, and
includes his personal coming-out story.

 
Act III, “Collective Action to Overcome Injustice,” explores his Jewish heritage and includes scenes from his play on Jewish immigration, “Why Should It Be Easy When It Can Be Hard.” One of the most touching scenes interweaves vintage clips from a Nazi propaganda film of a production of Hans Krasa’s children's opera “Brundibar” in the Theresienstadt concentration camp with scenes from a contemporary production adapted by Mr. Kushner and designed by the author and illustrator Maurice Sendak.

 
 The documentary ultimately settles for being less than
the titles of its three acts imply. As it follows Mr. Kushner dashing around New York to various functions and makes a uick trip to his country house in the Hudson Valley, it creates an entertaining, intimate personal profile. We even hear about his 100-pound weight loss after writing “Angels in America.”

 
Mr. Kushner is forthright about his homosexuality, which he recognized at age 6 and struggled against into his college years. His father, filmed in Lake Charles at his 80th birthday celebration, candidly talks about his initial difficulty accepting his son's orientation. He now boasts of being “Tchaikovsky’s father.”

 
Although the movie shows Mr. Kushner's weddinglike commitment ceremony with his partner, Mark Harris, gay marriage as a political issue is not addressed, nor does the movie go into the history of their relationship.