About Mario Mercier there are some interesting stories. A director with a short career, for some he was a Satanists, or attracted to esotericism, who then turned to New Age and writing books about nature, shamanism, and spiritualism. He is close to the spirit of Rimbaud, Boheme, Borges adds Wikipedia.
His third and last movie “A women possessed” seems close to  Polselli or a Batzella and of course with Jean Rollin. There is the shadow of the Breton director, precisely the one of his less inspired period and about Polselli/Batzella we can say that we are just in front of their French version.
All this makes it easy to guess what "La Papesse" is. A poor production with homemade satanism and tits.
The story tells about Laurent and Aline. Two spouses. He is a kind of artist who meets the Papes Jesial sect that submits him to many tests before accepting him. Aline also wants to be part of it, but she will be the victim in a Sabbath before being eat by a dog. Laurent will give Jesial a satanic descent before being killed.
In a rural France between meadows, rocks and huts, Mercier shot this crazy and definitely crafty story, in which we didn’t feel the satanic power but only its parody.
Violence and sex are also a trash parody in a story, useless to say, rather trivial. The top is with the unbridled Sabbath that more than that it feels like a hippie party out of time.
We hoped that at least in the erotic aspect one could save something. But we have only torn clothes and tits put on for free and above all low quality.
"The Papesse" is a good B Movie with some performers (Lisa Livanne, Erika Maaz and Jean-François Delacour) who have managed to make career in the entertainment world and maybe forget this job. Lucky them.