The trailer would have you believe this is a true horror movie, one which is comparable to the Exorcist.
I am here to tell you it certainly is a horror movie, but not for the supernatural elements (a point I'll touch on later in this article) and it certainly isn't comparable to the Exorcist - why is this?
Well...here we go!
*Filled with spoilers! ...just so you know...
The story revolves around a family, of which the grandmother dies - which stirs up a lot of issues in the past for the kids and the mother. The mother has a history of mental illness in the family - of which almost all of her immediate family died before she created her own.
Her brother and her father had schizophrenia and dissociative personality disorders - the ultimate causes of their premature deaths.
[Just a reminder here - mental illness is hereditary - genetically speaking.]
I've seen many Youtube videos speaking about the film and the ending - they all seem to satisfy themselves with exactly what they see and don't question if the scenes had any 'hidden' meanings. So, as you can imagine, almost all of them think this is the story of a demonic cult created by the grandmother who died - trying to bring forth a demon from hell to inhabit a certain male member of her family.
This, however, from my perspective and the perspective of people I've gone to see the film with was completely wrong and too simple of an answer for such a complicated piece of art.
The author himself (who is also the director) pointed some of these things out:
in an interview which you can find on Youtube, he explicitly said he wrote it primarily as a drama to depict what mental illness looks like inside a family - it's supposed to be (his words) "a vivid family drama" first and foremost. It is also described by the creator as supposed to be sorrowful and a serious meditation on grief and trauma.
So these quotes, to me, are clear indications he himself is also primarily focused on mental illness and all real-life human problems when connected to those issues.
Now - about the supernatural elements in the film.
There were quite a bit of those near the middle and the end - they were all witnessed solely by the son and his mother - both of which have tremendous predispositions for mental illnesses/disorders.
(As you must know - mental illness can be triggered or worsened by trauma - which is something they all experience at the beginning of the movie more than once.)
The supernatural elements can clearly be explained as hallucinations from their afflictions - and explained also by the fact that the audience sees the world through their eyes and not a sane person's viewpoint.
Another element which lends itself to this movie being an ode to the sufferers of mental illness is that the father/husband seems to be fighting this, at first convincing his wife of calming down and seeing the world as it is, and later on being killed by the wife in a schizophrenic rage - which she doesn't see as murder, but as auto-combustion of her husband and she is genuinely shocked.
The insane aren't shown as crazy, they're shown as victims and prisoners of their own minds - which they truly are.
Historically speaking many schizophrenics and people with disocciative personality disorders were called possessed and were put through exorcisms - this is where the Exorcist comes into play - but it is only a small nod to the genre while keeping the rawness of reality with the audience at all times.
The writer and director is brilliant at approaching the topic and making it seem almost demonic - since mental illness isn't even today understood as well as it should be - since it isn't scannable or visible - might as well not exist.
This film was a piece of art in every sense of the word. The horror genre creeped in there - solely because of the rawness of the mentally ill human's condition that stalked me as I sat there watching it - and all the way home.