"Christianity", a long-term atheist friend of mine says, "has something distinctive to say about forgiveness." Her words came into my mind as I watched the TV footage in which some of the bereaved victims of last week's Charleston shooting offered forgiveness to the man charged with the crime, Dylann Roof.

The 21-year-old white supremacist has been arrested after the shooting of nine people at the Emanuel African Methodist Episcopal Church on Wednesday of last week. Mr Roof seems to have been convinced that black people were "taking over the world"; he said he wanted to "do something for the white race". In his first court appearance last Friday, Mr Roof showed no signs of remorse. He was emotionless, sullenly compliant, and deeply pathetic.

In contrast, the victims were dignified, even in their grief. This well-known community church, with its long links to the Civil Rights movement, has nurtured a kind of Christianity which is deep and multifaceted; rooted in the gospel in such a way as to make the paradoxes of the faith live afresh for all of us. This is a place in which it is possible to rejoice and mourn at the same time; to feel anger and outrage, and yet to have compassion for those who "know not what they do".

Christianity is not the only faith tradition to recognise the importance of forgiveness, but it does so in a very particular way. There is no blurring of the boundaries between right and wrong; no accommodation of evil as a necessary aspect of the wholeness of things. The triumph of goodness comes in the recognition that even the most depraved killer or pervert is a person with a soul, a being ultimately capable of receiving salvation. Goodness lies at the root of things, not evil; and to forgive is to bear witness to this fundamental truth.

It looks as if Mr Roof had an experience of ordinary human goodness when he was welcomed by members of the prayer group on his arrival at the church. He sat with them for an hour, apparently touched by their "niceness". Perhaps at that moment he knew what he was up against, and hesitated. But, eventually, the evil demons appear to have won.

Although the bereaved may forgive, the State does not. South Carolina upholds the death penalty, and the Governor has already said that prosecutors will press for it in this case. But perhaps the spontaneous Christian attitude of the victims will have a long-term effect on a society that is still in thrall to its gun lobby, and still executes too many pathetic misfits.