Okay, so it’ll be set in the future, when Christianity is a persecuted religion, and it will follow the lives of several young people who are all taken by the government’s secret police from a ‘fanatical’ and ‘dangerous’ gathering.
The main character (who is the only one whose plotline I have really thought out) is drafted into the military and used for menial labor and cannon fodder. His persistent good attitude and willingness doesn’t have any effect on his Christian-hating commanding officer, who makes him do all the unpleasant jobs in her camp, like scrubbing the toilets with a toothbrush.
His part in the story ends when he sacrifices himself on the battlefield to save her life, and she realizes that he actually believed in something real. She becomes a Christian and starts working to change the system.