Hollywood A-lister Chris Pratt is throwing his support behind a new movie that tells the story of the often-unsung heroes of the military - combat chaplains.

The new film Fighting Spirit: A Combat Chaplain's Journey, opened in US theatres on November 8, and is directed, written, and produced by Hollywood director and producer Richard Hull.

"I knew nothing about military chaplains," Hull told CBN News. "I didn't even know that that existed as a profession."

As he started researching the work they do, Hull said he soon became personally invested in the incredible backstories of some of the men and women who fill a unique role in the armed forces.

"The more I got to know the subject matter, the more I fell in love with it, and I thought, 'This is a movie that, not only do I want to produce, but I also want to direct and be the storyteller behind it,'" he said.

Hull said finding backing for the project came easily, with actor Pratt, a committed Christian and veterans advocate, coming on board as an executive producer.

Pratt, who was originally known more for his comedic roles thanks to Emmy winning television show Parks and Recreation, has become one of Hollywood's leading action stars after starring in blockbusters like the multi-billion-dollar Marvel franchise.

He is also well-known for his willingness to openly share his Christian faith despite often attracting criticism due to his beliefs.

"He's a big military supporter," Hull said of Pratt.

"He's a very faith-forward guy. He really has a true heartfelt interest in telling these stories, most of which have never been told."

As Hull dived deeper into the experiences of chaplains, he discovered that there was far more to their role than he imagined, often requiring them to put their lives at risk just as much as the combat soldiers they serve alongside. In US military history alone, 419 chaplains have laid down their lives to serve others.

"On the one hand, chaplains go into combat wearing a uniform, but not carrying a weapon," he said. "It's a profession that...you do it for some higher calling."

Hull said that he wanted to show the impact chaplains have in both times of war and peace, and how they are there for those serving in the military whatever the need, from spiritual guidance to saving lives on the battlefield.

"They're just present and they're dealing with these moments of life and death with soldiers, young and old — and families," he said.

"And it's really intense, and it's really powerful, and it's very existential, and a chaplain may come from a particular faith, and all faiths are represented in the chaplain cores of all the different military branches."

With a history of service that goes back to George Washington, Hull said the movie would show why chaplains are 'revered' within the military, offering what he calls a "true look at what these people, as humans, go through and the power that they have".

But, Hull said that the movie would also offer an honest portrayal of the costs of being a chaplain, with many chaplains admitting they often struggle with issues like 'compassion fatigue'.

"When you go to war, you're going to come back a very different person," Hull said. "And war can leave scars on your soul."

Hull hopes Fighting Spirit: A Combat Chaplain's Journey will help open the public's eyes to what it means to be a military combat chaplain, and see what it means to live your faith "in the chaos of war".