THIS is a Taj Mahal of correspondence — a monument to married love. It is also a work of filial piety, compiled, introduced, and annotated by the children of this remarkable and well-matched couple, the straightforward Freya and the more complex James (as he is called here). It contains more than 150 almost daily letters, smuggled in and out of Tegel Prison by the saintly chaplain Harald Poelchau and his wife, Dorothee, who risked their lives to preserve them and sustain the relationship.

The von Moltkes were opposed to Nazism from the start. They gathered a representative group of like-minded people on their estate at Kreisau to discuss the future of Germany after the war. As the situation worsened, so their faith increased. He opposed a political coup and the Stauffenberg plot, but was accused of defeatism and of failing to warn the authorities. At his trial, the notorious People’s Prosecutor, Roland Freisler, conceded that he was being sentenced for thoughts, not deeds, for envisaging a future based on Christianity, both Protestant and Catholic. He thus died a martyr, and an ecumenical and European one at that, though both he and Freya always rejected that word.

The letters are truly Pauline. He is in chains; he asks for books, paper, and clothing; he is helped by kindly guards to stay in touch with the household of faith; he exchanges greetings and prayers; but, above all, he concentrates on the love of God, and of his wife. They spend much of the time discussing the scriptures, and, very Lutheran, the hymnal. He considers himself, and Freya considers him, already dead. They draw comfort from Kant’s notion that at death we pass from time into eternity and, whether we live or die, are present to one another and to God, as well as from the idea that there is no contradiction between entrusting oneself wholly to God and trying to save one’s life.

So they prepare his defence and appeal for clemency. The capriciousness of Nazi justice plays cat-and-mouse with their feelings; and the heights and depths make harrowing reading. There is insight into the mystery of Calvary, as James thanks Freya for her willingness to sacrifice him, when a word from her would have kept him back. She replies: “I live not to myself but to God.” That is the clue to their deep unity of heart and mind. One night, he dreams that they are Siamese twins. As I read that, I came some way to understanding, as if for the first time, the concept of “one flesh”.

In an afterword, Rachel Seiffert writes poignantly as the granddaughter of convinced and convicted Nazis. I was privileged to work with her mother on the reconstruction of East Berlin in an ecumenical fellowship that persists to the present day. In the same spirit of overcoming the past, Kreisau (now in Poland and renamed Krzyzowa) has been transformed into the Foundation for Mutual Understanding in Europe. It was the scene of the Mass of Reconciliation between Germany and Poland 30 years ago.

The Very Revd Dr John Arnold is a former Dean of Durham.

Last Letters: The prison correspondence, 1944-1945
Freya and Helmuth James von Moltke
Helmuth Caspar, Dorothea, and Johannes von Moltke, editors
Shelley Frisch, translator
NYRB Classics £14.99
(978-1-68137-381-2)
Church Times Bookshop £13.50