The premise of “Last Exorcism” is strikingly reminiscent of the (real) 1972 documentary “Marjoe” about child evangelist Marjoe Gortner who, having grown up and left the church, invites a camera crew along for one last revivalist tour to expose the chicanery of charismatic preachers. In the case of “Last Exorcism” Marcus’ aims in inviting the crew along is to expose the fake exorcisms that he (and presumably others) have been doing for years.