The A.R.T does it again with WITNESS UGANDA a vibrant, moving world premiere production, that tells a modern true story of the power and the dark side of philanthropy(!) and stars the actual gay, black, Christian man who lived it. That man is the ultra-personable Griffin Matthews, a charismatic young performer who was kicked out of his church choir after declaring his homosexuality. Sick of trying to get the only parts available to him as an NYC actor –“drug dealers and jungle animals”–he hopped on a plane to Uganda in 2005 to find himself by volunteering at an orphanage. What he found there was corruption and a calling: a group of stray kids begged him to teach them what he knew.  Unable to forget his students and their stories after returning to New York, he began raising money for their education and founding a non-profit called “The Uganda Project.”

This is one unusual melange; it instantly grabbed me– I mean within seconds, before I even fully understood what was happening. The young people’s stories and Griffin’s experience are commingled in this autobiographical musical co-created by Griffin and his composer/partner Matt Gould; it’s all directed by Diane Paulus whose instincts here are dead on. The staging is a thing of beauty: a huge live orchestra stage right, propels the action with a gorgeous score of soul-searing melodies and a mash-up of African and western rhythms. Gauzy curtains fly by unveiling beautiful, moving tableaux, while huge video screens reveal African vistas, and swirling projections of clouds and stars seem to envelope the physical and spiritual worlds. Dancers sweep seamlessly in and out the action, even gathering time and space to give Act I the power of myth. And the voices? These singer/dancer/actors will thrill you to your bones with their urgency and passion.

The story unfolds in two acts– and Act II does need work. There is a video image of a central character in a pivotal moment which is ultimately misleading and left me scratching my head, even feeling cheated. Answers beg to be fleshed out here. Too, Griffin’s own journey of self-discovery and those of the young people whose lives he seeks to shape, need to be more pointedly and dramatically intertwined; the questions these actual events raise around philanthropy and “giving” could be more deeply probed: Can we change people? Should we? How? Is “helping people” merely ego-based arrogance in disguise?

Nonetheless, this is an awesomely powerful show– full of passionate, alive performances, and a real story that is still unfolding. WITNESS UGANDA throbs with propulsive momentum, like the beating of a warm human heart on a cold winter’s day. Don’t wait for the next snowstorm to see it.  Through March 16 at the AMERICAN REPERTORY THEATER in Cambridge.