Want to find a movie about a play

The film starts by showing that a bunch of rich people are watching a play. A character is brought onstage and gives birth to a baby that is supposed to be a Jesus-like figure. Mary steals the baby and claims it as her own. The theatre-goers are able to interact with the characters on stage and decide how the story will progress. At the end, the Jesus character is murdered by Mary. Very weird movie. Don’t know the name.