Come Sunday has one major thing going for it: Ejiofor’s tremendous performance. Since his Oscar nomination for 2013’s 12 Years a Slave, Ejiofor hasn’t quite seen his career take off in the way I would have wanted it to. But he remains one of the most dynamic leading men in Hollywood, and his work here far surpasses the material he’s given. Ejiofor is the only actor in this (generally strong) ensemble to really capture the ambiguity that Marston and the film’s writer, Marcus Hinchey, are clearly fascinated by.

Pearson’s change of heart is mysterious and sudden to everyone around him, but Ejiofor conveys just how resolute the character feels that his old beliefs are wrong—even if he hasn’t yet defined the parameters of his new philosophy. If Hell exists, and souls are condemned to an eternity of damnation and torture, then doesn’t that make God evil? This is the big question Pearson is compelled to ask, even as it horrifies his congregants.

He argues that damned souls (he brings up names like Hitler) and people who never accepted Christianity will nonetheless be reconciled to God and welcomed into Heaven. It’s enough to drive out most of the worshippers at his 5,000-member church in Tulsa, Oklahoma, and it eventually lands him in front of the Joint College of African American Pentecostal Bishops, who declare him a heretic. But Marston communicates this high drama in a tepid, disjointed matter: He alternates between staging serious conversations behind closed doors, and scenes of Pearson preaching in which audience members walk out unhappily.

None of it feels as cataclysmic as it obviously was in real life, and only Ejiofor taps into the seismic nature of the conflict. A slew of talented actors fill out the rest of the ensemble: Jason Segel plays a fellow preacher, Henry (who is upset about Pearson’s departure from church dogma); Martin Sheen is the famed televangelist Oral Roberts; Danny Glover contributes a few scenes as Pearson’s uncle, as does Condola Rashad as Pearson’s wife. The only other performer who really stands out alongside Ejiofor is the always impressive Lakeith Stanfield, who plays an organist at Pearson’s church who begins to fear that he’s doomed to Hell by associating with the bishop.

The real-life story that Come Sunday explores is intriguing, but it seems better suited to a documentary film or series that could delve more deeply into the intense theological debates going on, and into the history of Christian thought being challenged. Marston just doesn’t have the time to do that, instead making his movie a very personal tale of one man grappling with his beliefs. Ejiofor does valiant work trying to make that enough to justify the film’s existence, and he almost succeeds. But I came away from Come Sunday wanting so much more.

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