'I wasn't able to pray. It took me years to recover'

A former nun who left her order hating God, then became a prolific theologian, has at last returned to faith – but still has no time for organised religion

Karen Armstrong has written more books on religion than she would care to remember. There have been biographies of Muhammad, the Buddha, St Paul, back again to Muhammad, and now, with her latest offering, the Supreme Being himself in The Case for God.

Tucked away in the recesses of her impressive oeuvre (22 books in as many years), however, are works that now embarrass her – "there are some books I'd rather not remember" – but of which her academic foe the arch-atheist Richard Dawkins might heartily approve.

But this earliest corner of her bibliography shows just how far she has come in her own spiritual journey. And what a painful trajectory it has been, from a working-class West Midlands home – she was the first in her family to make it to university (Oxford, no less) – to a disastrous period as a nun, which led to anti-Christian fervour, raging godlessness and the production of these "clever, clever Dawkinsesque" early books, as she calls them, clucking with remnants of a Worcestershire accent to undercut her intellectual grandiosity.

Sitting in the front room of her immaculate home off Upper Street in swanky north London – coiffeured, powdered and elegant at the grand old age of 64 – she remembers buffetting between failed academic and television careers, to poor health, to black depression and near penury in a one-bedroom East Finchley flat, to existential trauma. All before international celebrity as a world-class academic of comparative religion, of course.

"I remember on my 45th birthday I woke up with huge depression, and thought 'I've done nothing with my life,'" she says.

Her religious endeavour started with a "rebellion" against her parents when she announced that she was joining an order of nuns at the age of 17. "They were appalled. My parents went to mass on Sundays because that was what was done."

The rebellion cost her dear. Her experience at the convent left her angry and God-hating. "I was very aggressive towards religion. I was very broken. I didn't believe in God, I thought it was all rubbish. I wasn't able to pray. It took me years to recover. If I saw someone reading a religious book on the Tube, I would want to get in another carriage. You could say I'm in convalescence now."

The wilderness years continued until that seismic moment, in the one-bedroom flat, aged 45. After completing an English literature degree at Oxford, she lived the teen years she never had in her early thirties, falling in and out of love with a string of hopeless men. She battled with terrifying episodes of epilepsy, which went undiagnosed for 30 years ("I was seeing and hearing things that weren't there. I thought I was going mad. I was thrilled when I was eventually diagnosed."). She attempted to complete a DPhil but had her thesis rejected, lost a teaching job through ill health, forged a TV career for a few years in the 1980s, but ended up wondering how she would make ends meet.

Enough challenges to test the patience of Job, one might think, but she sees a pattern at work. "All the time, it was part of a process. If I hadn't left the convent, I wouldn't be talking to you now."

Armstrong lives alone and has been surrounded by women for most of her life, and strong ones at that: a mother (no longer alive) who kept the family afloat when her father lost his livelihood, and a sister to whom she is now not very close and whom she describes as a "Californian Buddhist". "I come from a very matriarchal family. My mother was strong. She got a job in a medical school when my father became bankrupt. She went in on a secretarial level and ended up running the department. She was clever, but had no education then. She ended up doing an Open University degree which was presented to her by Betty Boothroyd in the 1990s."

Men appeared in her life relatively late, but none stuck. She said some years ago that she never thought men found her appealing in her youth. When I ask her if this may not be better phrased the other way round, she agrees that perhaps it was, after all, she who didn't find men appealing.

"I went into a convent, then a women's college at Oxford and I didn't come across many men. I have been in love, but with people who have tended to be no good."

She's glad to be single now – "I wouldn't have been able to do all I have done, all the book writing" – but the judgement of others has not always been kind.

"It's getting easier for me now. It was harder 10 years ago when friends were all couples and some treated me as if I were a child. Some women seem to believe that you have not gone through a [necessary] rite of passage until you've gone through childbirth and are putting up with some annoying husband.

"Until then, some believe you're irredeemably immature. There used to be a lot of patronising remarks, but they've stopped now."

It was shortly before her television career ended, in 1984, when making a documentary in Jerusalem, that she found her spiritual mojo. Researching the life of St Paul, she was still virulently anti-Christianity when she began to observe the diversity within religion in Jerusalem, and had her own "road to Damascus" moment. It was then that she began writing A History of God, her first critical success.

"There I was, living in East Finchley, and I thought, I have to write something. I needed to make some money. I expected this book to follow in the same line of scepticism as my TV career, to be Dawkinsesque.

"But then something happened. I found myself working on my own, with no TV people to egg me on. I found silence and that began to alter my relationship to these texts. Theology is like poetry; you can't read poetry in a crowded party."

Silence looms large in her current book, in which she presents the case for the ultimate unknowability of God, but argues that you can catch glimpses of the divine or "moments of transcendence" through silence, religious practice or any creative endeavour. It is "poor talkative Christianity", she says, that distracts from intimations of divinity. "It's not that I think we have to all become Carthusians, but I'm for silence in our approach to God. Protestant Christianity is so wordy. You never give God a chance to get in edgeways. You're always telling Him how good and wise He is."

But neither does this silence have its rewards, she adds. The mistake many people make is to expect God to enter their sensory world. "You're not in it to feel a warm glow. I thought it was my own failing that I didn't feel this at the convent."

The other principle that transformed her work was learning to have empathy in academic research. "I learned about the science of compassion, putting yourself in the other's position, in a scholarly sense. I thought this was absolutely right for me or I would go on writing heartless, pointless books.

"It meant that the clever, Oxford-educated, career-driven ego had to go on the backburner. I had to leave that behind. That's the way I've proceeded since then."

Since her first book in 1982, she has reeled off tome after tome on scripture, the history of Islam, Buddhism, Christianity and Judaism that have appealed to a general readership and theologians alike.

Her latest endeavour was planned as a riposte to the likes of Dawkins, whom she calls a "secular fundamentalist" because of his unbending views. "Dawkins and the others make perfectly good points, if they didn't put it quite so spitefully. A good atheist critique is very important for theology; it stops theology from becoming idolatrous."

What of her own sense of religion now, I ask. She says she takes a mix-and-match approach: she took part in church services while at Harvard, but she also goes to Buddhist ceremonies, and Islamic ones. One day she'll probably pin her colours to one mast, she adds, but until then, the silence and the contemplative sense come from her writing.

We chatter about the struggle for meaning and truth and God and life; she is animated and voluble. It is self-help for the soul that Armstrong offers, I think, or just that rare moment of transcendence before one has to go back to the everyday.

The Case for God: What Religion Really Means by Karen Armstrong is published by Bodley Head

Biography

1944 Born in Wildmoor, Worcestershire. Family later moves to Bromsgrove andthen Birmingham.

1962 Becomes a nun at the Society of the Holy Child Jesus.

1969 Leaves the convent to study English at St Anne's College, Oxford.

1976 Becomes an English teacher at James Allen's girls' school in Dulwich but has to leave after six years, suffering from epilepsy.

1984 Presents a Channel 4 documentary on the life of St Paul, describing it as a "breakthrough experience".

1993 Writes the best-selling A History of God.

2004 Is honoured by the New York Open Center for her "profound understanding of religious traditions".

2006 Criticised by the head of Mediterranean studies at King's College London for creating a "travesty of the truth" in her book Muhammad: A Prophet of Our Time.

2008 Awarded the Franklin D Roosevelt Freedom of Worship award for her "religious understanding, teachings on compassion, and appreciation for the positive sources of spirituality".