The movie tells the survival story of a mute woman called Liz, played by Dakota Fanning, who is stalked by a vengeful preacher, portrayed by Guy Pearce.
It is one of 20 films competing for the Golden Lion that will be awarded on Sep 10.
"I have always been a big fan of the genre, it is just that I have also been a little bit intimidated by the genre because there are so many great movies," Koolhoven said at a news conference ahead of the movie's premier.
The Dutch director decided to shoot the film in English.
It is a co-production between six countries -- the Netherlands, Germany, Belgium, France, Britain and Sweden -- which the director said granted him bigger flexibility to "make it what we wanted" than if it had US funding.
Fanning said portraying a mute character almost throughout the movie was a particular challenge.
"I'm fascinated with the way people communicate without words in just everyday life, I think the energy, the body language, and overall vibes can say so much more than the words that we say to each other," the 22-year-old US actress said.
Religion and violence are strong themes in this survival epic set in the American West, but shot in Europe, and Koolhoven said being graphic was deliberate to make the story credible.
"I would feel morally very dubious if I made that violence too comfortable, it should be uncomfortable, and if it’s too easy to watch then I am doing something wrong," he said.
Fourteen-year-old Emilia Jones, who plays the heroine as a child, said some of the images were so violent that Pearce was hesitant to do some of the things prescribed by the script.
"But it was very key to the script and the minute we said cut he'd hug me and say 'I'm so sorry'," she said.
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