Matthew Edgeworth’s review published on Letterboxd:
The Witch is a masterpiece of modern cinema and a debut which marked Eggers as an auteur in the vein of some of cinema's greats. It is a stunning, art-house horror.
The Witch does not deliver cheap jump scares, but instead establishes an overwhelming sense of dread. It is an extremely slow-burn, filled with anxiety. From the very opening we are met with a constant tension which is not released until the film's climax. However, genre is a constrictive thing. As much as horror I would say The Witch is a psychological drama grounded in the particulars of it's family sphere. It is a film which is equally rooted in its historical setting. With meticulous detail Eggers brings the world of 17th century Puritanism to life. Despite dealing with horror and the supernatural, it's historical authenticity is vastly superior to the vast majority of nominally 'historical' films.
Through his extensive research and the vivid manner in which he recreates their world, their language and their theology Eggers successfully conveys the Puritan pysche itself. That we so closely inhabit their world-view only adds to the horror of the film. It is not simply that the characters are menaced by a religious monster and the forces of evil (witches obviously being in league with the devil) it is that they are menaced by the very ideas and dogmas that make up their religion (original sin, the impurity of others, concern over burial rites, etc). The paranoia this causes torments the family just as much as the actual Witch does. Their fears over sin, pride, lust and so on, turns them against each other, destroying their relationships. The film thus acts as a profound critique of the Puritan mindset. Their own world-view is what ultimately tears the family apart. Tomasin does not start the film as an evil witch, but she becomes one as a result of the logical consequences of this paranoid (not to mention sexist) society.
However, although there is some deliberate ambiguity in the film as to the extent to which the events it depicts are real, conjured by the Puritan mindset or a hallucinatory consequence of Ergot poisoning, I would take it that everything happening on screen is literally taking place. It is a smart horror, but a horror nonetheless.