Why did Desmond T. Doss refuse to bear arms during WWII?
Fact-checking Hacksaw Ridge confirmed that he refused to carry a weapon because of his personal and religious beliefs as a Seventh-day Adventist, which is part of the Protestant sect of Christianity. "My dad bought this Ten Commandments and Lord's Prayer illustrated on a nice frame, and I had looked at that picture of the Sixth Commandment, 'Thou shalt not kill.' There's a picture that had Cain and he killed his brother Abel, and I wonder how in the world could a brother do such a thing? I've pictured Christ for savin' life, I wanna be like Christ go savin' life instead of takin' life and that's the reason I take up medicine."
A defining moment in Desmond's life that perhaps helped to further shape his attitude toward guns and violence happened when he was a boy. His father and uncle were drunk and got into a fight (the movie implies the fight was between Desmond's father and mother). His father pulled a gun on his uncle but his mother stepped in. She called the police and told Desmond to hide the gun. After doing so, young Desmond returned just in time to see his father being loaded into a black police wagon in handcuffs. Desmond believed that his father would've killed his uncle (his mother's brother) if his mother hadn't stepped in. Desmond vowed that would be the last time he ever touched a gun. -The Conscientious Objector Documentary