Franco stars in the title role as real-life gay activist and magazine founder Michael Glatze who, according to press notes, was "'saved' from his homosexuality after turning to God and eventually becoming a Christian pastor."
Cahoon will play Peter Ian Cummings, founder of XY Magazine, where he was Glatze's boss and friend. The cast also includes Zachary Quinto and Emma Roberts.
The motion picture, directed by Justin Kelly, is based on the article "My Ex-Gay Friend," which was written by Benoit Denizet-Lewis for The New York Times Magazine in 2011.
Cahoon created the roles of Ed the Hyena in The Lion King, George in The Wedding Singer and The Childcatcher in Chitty Chitty Bang Bang. He also starred opposite Matthew Broderick in the Roundabout's revival of The Foreigner, for which he received a Lortel Award nomination, and was seen in The Shaggs: Philosophy of the World at Playwrights Horizons, How I Learned to Drive at Second Stage and The Rocky Horror Show at Bucks County Playhouse.