Rawhead Rex

Howard Hallenbeck (David Dukes) travels to Ireland to research items of religious significance. He goes to a rural church to photograph some graves. Meanwhile, three farmers are attempting to remove an ominous stone column from a field. Two of the farmers head home. A thunderstorm appears out of nowhere, and smoke pours from the ground. Lightning strikes the column. The monster Rawhead Rex rises from the dirt.
Howard meets Declan O'Brien (Ronan Wilmot), who directs him to Reverend Coot. The curious O'Brien approaches the altar and places his hand on it. Images flash before his eyes. This experience apparently destroys O'Brien's sanity. Afterwards, Howard inquires about the church's parish records. Coot says he can arrange to have Howard look at them.
Later, a man arrives at the home of locals Dennis and Jenny. He discovers a clearly traumatized Jenny. Police arrive. Rawhead drags Dennis's dead body through the forest and comes upon a trailer park. A teenager named Andy Johnson is trying to make out with his girlfriend. The two teens head into the woods. Soon after, Howard sees Rawhead on top of a distant hill with Andy's head in his hand.
Afterwards, Howard speaks again with Coot, who tells him the church's parish records have been stolen. Declan O'Brien destroys his camera. He takes his family on the road again.
On the road, Howard's daughter needs to go to the bathroom, so Howard pulls over and lets her go by a tree. Hearing her suddenly scream, Howard and his wife rush to her; Howard's son stays in the van, alone. Rawhead kills Howard's son and takes the body into the woods. Infuriated by the police's unsuccessful efforts to track down Rawhead, Howard returns to the church. He discovers that there is a weapon shown in the stained glass window that can be used to defeat the monster. After Howard leaves, Coot curiously touches the altar but resists the temptations and images it shows him.
Rawhead arrives at the church to baptize O'Brien by urinating on him. A bewildered Coot goes outside to investigate the noise and sees Rawhead. Horrified, Coot flees inside the church and into the basement while Rawhead destroys everything inside. Coot finds the missing parish records, showing what appears to be some kind of blueprint of Rawhead himself. The insane O'Brien catches Coot and forces him upstairs to be sacrificed to Rawhead. The police arrive at the church and prepare to open fire on Rawhead, but they hesitate because he is carrying Coot. The brainwashed inspector dumps gasoline around the police cars and ignites it just as they begin to shoot at Rawhead, killing all the police, including himself.
Howard leaves his wife and daughter and goes back to the church where a dying Coot tells him that Rawhead is afraid of something in the altar. Howard goes inside where O'Brian is burning books and is overpowered by Howard. Howard, by using a candle stick, opens the altar and gets to the weapon. O'Brian retreats to Rawhead to tell him, leaving Rawhead displeased. Howard tries to use the weapon, but has no effect. In anger, Rawhead kills O'Brian by tearing out his throat, with Howard's wife watching in terror.
As Rawhead tries to kill Howard, his wife picks up the weapon, it activates, stopping Rawhead from killing Howard. A ray of light comes out of the weapon and hits Rawhead, hurting him. Howard realizes that it has to be a woman for it to work. Then the form of a woman appears from the stone and shoots electric rays through the stones and into Rawhead's body, knocking him to the ground. After a few more blasts, Rawhead is drained and weakened to the point where he has no hair, has aged, and is ill and dying. Finally he falls through the ground with Howard's wife dropping the weapon in with him. Rawhead is smashed under giant stones and finished. Both Howard and his wife cry in light of it being over.
In the end, the boy from the trailer park places flowers on Andy Johnson's grave. As he walks away, Rawhead emerges from the ground and roars.

Question: How does Rawhead kill O'Brian?
Answer: tearing out his throat