Stigmata are unexplained phenomena that have been known to affect certain deeply religious people over the centuries. Bleeding wounds appear on the subject's body, mirroring the wounds of Christ on the cross. The film seems confused between this holy experience, and the opposite experience of demonic possession. Frankie alternates between being "normal" and acting like Linda Blair in The Exorcist. The film is an utter mess and seems to have no idea of what it's doing. During the action-packed scary bits, it's just like a bad music video, using a confusing blend of high contrast, high grain, bright, dark, fast editing and a whole bunch of unrelated camera angles in which there is no proper continuity. I can't stress how much I hate the way this film was directed. It's taken a very interesting subject and made a mockery of it. The dialogue is pretty bad too, and I just don't believe the way Frankie takes it all in her stride and just wants to ignore the gaping wounds in her wrists because she's bored with all this weird stuff happening to her.
The only good thing about the film is that it's very funny. The way it portrays the Catholic Church is quite frankly hilarious, and I'm sure someone will have something to say about that. The trouble is, it's not meant to be funny. The end of the film contains one of the most embarrassing cheesy sequences I've ever seen.
If you want to see a film about demonic possession, see The Exorcist. If you want to see a film about stigmata, see Touch, which is a wonderful film that treats the subject properly. If you take my advice, you won't waste your time on Stigmata. Not unless you're in the mood for a good laugh.