Powerful Euro sleaze, by the good Jesús Franco, who also writes the script collaborating with other people. The story is quite interesting: a former priest, now a writer, redeems some women he considers sinners, torturing them to death.
An interesting idea which, however, is very poorly carry out,  even that (un)healthy BDSM boring that pops up here and several naked bodies of the actresses among which that of a young and very beautiful, Lina Romay stands out.
Someone wrote that it would take a director to remake it, with the necessary changes. I fully agree. In addition to boredom, then, a poor realization is added, with really bad special effects and a little inspired direction. Apart from that, there is something to save, and it's Franco himself. The Spanish director not at his best behind the camera, however, has a perfect mask for the role of the psychopathic priest, Mathis Vogel, the one who kills sinners. If you know Franco's appearance in the mid-seventies, you can only agree. He then acts with a very slow rhythm, excellent for the role and that with a good sound comment, present in the version I saw, the body of Lina Romay, and the atmosphere of Paris, closes the positive things.
“Exorcism” opens with Lina Romay naked and tied up and subjected to a very bad torturer. It is just a theatrical performance, which is part of an uninhibited world that ignites the atrocious fantasies of Mathias Voegel who begins to kill some women he spies while they are having sex. The police investigate these murders very vaguely, while always vaguely, the theatrical performances lead to an orgy in the audience.
There is very little to say or save as mentioned, and certainly the usual amount of versions, cut, uncut, hard core, many of which badly dubbed, certainly does not help watching a film that sees Franco not at his best. , although we are in the golden age. The cast includes other well-known faces of Franco's cinema, such as Monica Swinn and Olivier Mathot.