A summary of the movie follows. I spoil the entire thing, so stop reading if you do not want to know what happens. Really, I am going to reveal the major points of the movie...You have been warned.
So the movie starts sometime in the past (when women were burned as witches) with the torch-bearing townsfolk hammering a mask of the Virgin Mary onto a young woman's face. Next, a priest makes some exclamations and the woman is burned to a crisp. Later we switch to the present day. It turns out that the townsfolk from the past imprisoned the woman's soul in a doll (yeah, that old trope).
Our movie's hero (Jeffrey Dean Morgan) discovers the doll and shatters the chains wrapped around the doll. He is a down on his luck journalist who was disgraced when he fabricated stories. He is now condemned by his colleagues and cannot get a respectable job. To drum up interest in a tabloid story, he stomps on a doll that he discovers; he plans to write a scandalous story about evil plaguing the village cuz the doll is cursed. However, because he stomps the doll and breaks the iron chains on her little doll body, evil actually does escape.
It is soon revealed that the townsfolk were doing God's work by burning and torturing their captor. The woman (coincidentally named Mary) whom they tortured and burned was actually the bride-to-be of Satan. So smashing her face as they hammered the mask was holy work. If only that pesky journalist had not unleashed the evil. Why put unholy evil into a straw doll? What could go wrong?
Anyway, the evil Mary heals a deaf girl named Alice and uses her to perform miracles. A mob of people come to worship Mary/Alice. The entity Mary/Alice intends to possess the soul of everyone who pledges their soul to her three times (the say the name three times trope). But the journalist foils the nefarious plan when he tells the crowd/mob that he fabricated the story. According to the plot point, creating doubt will destroy everyone's faith. Even though three miracles had occurred, people ignored them and listened to the journalist. The doubt ruined evil Mary's plans to harvest souls. As revealed in the previews, the vehicle that Mary is using is the child Alice. I did say that there would be spoilers, but if this interests you, there is still a bunch of other mess I did not reveal. There is a small chance that you will be entertained if you dare to watch this, but that is because the move is unintentionally funny.
The Unholy is full of clichés, movie tropes, and stereotypical movie characters. It is almost a spoof of the horror film genre. All that they needed was a Barbie Doll at the beginning of the movie to trap the evil. If you decide to watch, good luck.