An outsider artist based in Cleveland, the Reverend Albert Wagner gained national attention by creating art from his experience as a black man living in America. Recurring themes of race, sex, violence, addiction, and spirituality in his work convey cautionary tales that are more customarily rendered as sermons. The self-taught artist did not find his calling until he was 50, yet his passion and conviction led him to create more than 3,500 pieces before he passed away in 2006 at 82.

Thomas Miller’s documentary “One Bad Cat: The Reverend Albert Wagner Story,” which makes its premiere Friday at IFC Center, is an absorbing portrait of a conflicted and often contradictory life. Indeed, Wagner led the kind of tormented existence that legends are made of. The reverend was no saint, and Mr. Miller does not shy away from Wagner’s early transgressions as an alcoholic, an adulterer, and a child molester before he found religion. Wagner cleansed his soul with paint, saying it was a divine directive. Some he had hurt eventually forgave him; others remained skeptical about his transformation.

The power and authenticity of Wagner’s creations are undeniable, but the film calls into question their sociopolitical implications. Many scholars and critics play armchair psychoanalyst in their attempts to decode Wagner’s work. Some think he painted the black experience with too broad a brush, while others wonder whether a nonblack audience can ever frame Wagner’s work in proper context. Does his art project internal racism? Do his “white groupies” succumb to liberal guilt? Can commerce and true art ever coexist? Mr. Miller attempts to address each of these questions in “One Bad Cat.”

Interviews with the subject would seem to complete a documentary like this one, but “One Bad Cat” might have been better off without them. In the documentary “In the Realms of the Unreal,” director Jessica Yu was able to beautifully mythologize the outsider artist Henry Darger in the absence of any interview footage with him. Despite the fact that Mr. Miller found Wagner during his last days, the reverend could muster little genuine introspection. Apparently, Wagner wasn’t as candid here as he was with other interviewers, such as the British journalist Nik Cohn, who noted Wagner’s desire for recognition and suggested his delusions of grandeur. Thus the interviews here fail to illuminate, and their very inclusion prevents viewers from sketching their own mind’s-eye portraits of the artist — the very thing that made Ms. Yu’s film so compelling.

“One Bad Cat” leaves some lingering questions about Wagner as a man of the cloth and about his religious work, which is unfortunate. But after dutifully presenting different views on Wagner’s art, the documentary does have something valuable to say about the relationship between the artwork and its beholders. It’s truly moving to hear testimonials from collectors who identify with subjects in Wagner’s paintings. That feeling is ultimately what makes his art priceless.