In the stories of Flannery O’Connor, grace is violent. It overpowers. Baptisms are drownings. It is only with a gun pointed at her that a grandmother can recognise the humanity of her murderer: she would have been “a good woman, if it had been somebody there to shoot her every minute of her life.”
This violence of grace is often represented by human violence, but it isn’t the same as human violence. Grace is beyond human comprehension, and so is impossible to represent literally. Any religious text is filled with metaphors, because metaphors are the only way to communicate about the divine. Using violence to represent grace, art can express how grace strikes: dramatic, overwhelming, painful. It is painful because it is transformative. Like violence, it is destructive, but it destroys only evil.