For the last four years at her Christian college, Gracie Turner had been keeping a secret. She had lost her faith. In high school, she watched cancer ravage her great-grandmother. Then she saw her family fall apart. One fight drove her to call the police on a relative. “I just remember thinking, why is this happening? How could this happen? And my first thought, or first person to blame was God,” Turner, a 21-year-old film major, told me. “I would lay in bed sometimes and just pray to God, like, it would be really nice if I didn’t wake up...