With two characters as well-kennt to the Charlotte Square village as Stuart Kelly and Richard Holloway, this meeting of minds was guaranteed to be entertaining and thought-provoking.

Kelly’s book, The Minister and the Murderer, seems at first to follow the same premise as Holloway’s less-recent book on the subject of forgiveness – indeed, Kelly pays homage to On Forgiveness, saying that it is one of very few books on the subject. Moreover, it is the fact that there’s very little forgiveness in society that makes Christianity itself very difficult, and makes this discussion so vital.

Where the two books differ is in Kelly’s weaving of autobiography, ecclesiastical history, and theology. As Holloway points out, this is a much-needed book on the history of the Church of Scotland, as well as a memoir of Stuart Kelly’s life, and his grappling with faith. One of the sections we hear read is introduced by Holloway as a ‘dose of Kant, dollop of Derrida, and plenty of Jesus.’

The central premise of Holloway’s book is from Derrida: forgiving the unforgivable. The point being that the most unforgivable sin is the one that most needs unconditional forgiveness. Kelly takes this argument on when he documents the story of one James Nelson, a man convicted of murdering his mother who, upon release from Saughton prison, wishes to be ordained into the Church of Scotland.

I’ll not spoil the plot for those who want to read it, since there was so much more to come out of this event than a mere introduction to a book. The point about forgiveness is that it frees more than just the offender. It potentially frees the victim. Derrida was terrified about what would happen in South Africa after apartheid, but who could have imagined a prophet such as Nelson Mandela, once described by Thatcher as a terrorist, would come up with the Truth and Reconciliation Commission?

As we learn that there is a moral cowardice in not being allowed to ‘let go’ and how resentment builds up, we are pointed towards the former Yugoslavia, or the Israel/Palestine situation, it is clear that the message of this book, and these two great minds, is colossally important. “Who,” they both ask, “Who is doing the big thinking?”

When Kelly talks about convicted sex-offenders having their windows broken, he points out how these mobs are simply monsters ganging together. The question of whether Scotland is more tolerant now is harder to answer than it was back in 1984, although at least the James Nelson story didn’t generate mobbishness. Now, one is only a tweet away from eternal un-forgiveness.

Forgiveness, then, is as complex a topic as it was when James Nelson’s case was brought before the General Assembly (amid petty sniping over same-sex relationships) or when Richard Holloway wrote On Forgiveness in 2002, or today, in 2018 as people continue to wilfully reject forgiveness. This sin against the Holy Ghost (which the Bible says is the only unforgivable sin) is what makes a book like The Minister and the Murderer “a colossal achievement” – as Richard Holloway says on the back cover – and a book that needs to be read by so many people.

For more on the Edinburgh International Book Festival click here.