Before I reached the end of the first paragraph, I realised that it would be wrong to laugh. The letter was ridiculous. But it was written in anguish. Clifford Shinn of West Runton in Norfolk had been driven as near to despair as his faith allowed by the previous Sunday's Songs of Praise. His agony was the result of "an unbeliever" appearing on the programme and speaking "with assumed authority about a Christian who has been mightily used of God". The unbeliever was me. During the two years since I published my biography of William and Catherine Booth, the founders of the Salvation Army, I have grown accustomed to letters assuring me that, although I confess to atheism, I longed to believe. But Mr Shinn - complaining about an interview in which I promoted my biography of John Wesley (A Brand from the Burning, published by Little, Brown) - had a different point to make.
"You have attempted to write the life of a Christian when, by your own admission, you do not know what Christianity really is . . . You could plunge into the records of Harrods and write a history . . .This would not harmonise with my account of that place where I worked for over 40 years. Your knowledge of Harrods, as with Wesley, is detached."
The notion that detachment might be a detriment is worth examination - though my objectivity was not, I think, the real complaint. The Satanic Verses are hardly objective about Islam. Mr Shinn may share Salman Rushdie's opinion of the Prophet Mohammed. But I doubt if he endorses his views on the One God who (Muslims and Christians believe) is the fountainhead of both religions. The subtext of the reproof was "only Christians should write about Christianity".
At least, atheists and agnostics should mind their own business unless they are prepared to write about religion in a religious way. There were few objections to George Bernard Shaw's Saint Joan because his Maid was obviously fighting God's battle against the temporal powers. Shaw may have laughed at the private soldier who believes that providence strikes down anyone who blasphemes in her presence. And his stage directions did not include an invisible actress simulating the voices of Saints Michael, Catherine and Margaret. But his Joan did perform secular miracles. At Orleans, she changed the wind so that the French army could cross the Loire, and at Chinon she recognised the highly disguised Dauphin. Then, after death at the stake, she was resurrected in the last act.
Christians reacted rather differently to Anatole France's biography. They particularly resented the account of Joan's refusal to be saved from the Inquisition by a plea of madness. Evidence in support of insanity included her attempt to repel a Burgundian attack by throwing turnips at the advancing army. Instead of revealing, as a saint and martyr should, that the vegetables had been supplied by God, she explained that they were the only missiles at her disposal. Rather turnips than nothing.
Whether or not the turnip incident ever happened, the attitude that it exemplifies is an admirable rule for life. The Joan who articulates that earthy indomitability is far more interesting than the plaster saint on her knees, holding her sword to symbolise the cross. Sanctity is a two-dimensional characteristic. And a more honest picture is painted by an artist who is not ashamed of the warts. That is the strength of the detached biography.
John Wesley led the Second Reformation, built a new church and helped to create modern Britain, but he was profoundly silly about women. Catherine Booth was the most extraordinary woman in Victorian England - brave, brilliant and resourceful. However, she neglected her children on God's behalf. Weaknesses do not detract from greatness. They simply make us marvel that men and women with human foibles can rise to such great heights. There is nothing inspirational about a hero or heroine who never felt temptation.
Yet letters I have received suggest that there are some Christians - small in number, but passionate in belief - who think that to admit any weakness in Christian heroes diminishes them and denigrates their religion. That feeling is, I suspect, the product of theological insecurity. The confident Christians accept that Peter denied Christ three times and St Augustine prayed for chastity, "but not yet".
Secure Christians accept their faith should be strong enough to stand a touch of cold reality. When, two years ago, I spoke to the Christmas Rally of the Salvation Army in Westminster Central Hall, it was with trepidation that I admitted my atheism. The applause that followed came, I thought, from an audience that was happy and clappy by nature. General Gowans - then head of the Army in Britain and now worldwide commander-in-chief - expressed the thanks of the high command. Bramwell Booth - William's son and successor - had, he said, addressed the Methodist Conference in that very hall and told them: "I see before me hundreds of good Salvationist faces." Some of the assembled ministers had mumbled their rejection of his description. So he had added: "Some of the best Salvationists don't even know what good Salvationists they are." General Gowans then put his hand on my head.
Perhaps I should have taken offence at being so obviously patronised. I felt only gratitude. Though I am certainly irritated by those letters telling me that, as a result of the writer's prayers, the Light of Grace will soon shine upon me. All I ask is that readers of my biographies who are lucky enough to have faith understand that their heroes are major figures in the history of Britain. John Wesley and the Booths were more than religious leaders. They helped to create my country. They belong to me as well as to the true believers.