A simple prayer guide designed for non-believers by a mathematician in his back bedroom in Edinburgh now helps people around the world to cope with the rigours of modern life. 

The text on the first page of the unassuming booklet sums it up: “27 million adults in the UK pray, 10 million regularly. Of the people who say they are not religious, one in five pray.”

The second page indicates the reasons why. “People have health scares and worry about relationships and the future. People stress about money and suffer from depression. Even with a full life we can feel empty and wonder if there is more to life than this.”

Over the past weeks Scotland has seen a major promotional campaign urging people to “try praying”. You might have seen it on the side of buses, advertising hoardings, railings and in railway stations.

It started in Edinburgh, but has spread around Scotland – supported by 600 churches and involving a print run of nearly one million – and around the world, with a major campaign in the pipeline in the US.

David said: “It is a much more private and secular society we live in and yet people do pray. Research shows that more than half of the UK’s adult population prays. It is a good thing and helps people. When we pray we talk to someone who is there. Even if people are fuzzy about what they think, the whole process is a help to them.”

He explained that the current climate is the perfect time for many people to consider praying. He continued: “The troubles people are experiencing at the moment are clear and this booklet tells them that there is more to life than this, that there is a God and he does hear their prayers.”

The huge reach of David’s booklet is as far as the author is concerned, testament itself to the power of prayer.

The founder said: “The money just seems to come in when we need it.” That included a recent sum from the Vardy Foundation, the charitable trust operated by Scottish motor dealer, Peter Vardy Ltd.

He continued: “It was never my plan to go into Christian work. I went to Birmingham University to study maths and spent nine months arguing with a Christian. I went there as an agnostic and my brother was an atheist. I was using his arguments but there were a lot more answers than I’d thought possible. Then this guy asked me if there was any reason I couldn’t believe and I didn’t have one.”

That moment changed David’s life. He said: “He asked me to receive Christ and I said, What here? No thanks.

“Then I was in the library and I asked God if he was there. I was expecting something to happen. I knew I had taken a significant decision and thought it would have been nice if an angel had appeared – but it didn’t.

“Two weeks went by and nothing happened so I prayed again, and I felt it was answered as the thought came into my head that God wanted me to trust him. The next day, I was in my room and I had such an awareness, of excitement, joy and peace, that Christ was in my life, which lasted three to four hours. I’d never experienced anything like it before and it overcame the sceptic in me.”

David joined a Christian organisation that worked with students where he remained for the next 23 years.

He had a ‘lightbulb moment’ at a Christian conference after talking to a woman who had given a 40-day prayer guide to someone.

He said: “I thought you can never give a 40-day prayer guide to an unbeliever, so why not write a short one for people who aren’t religious or don’t go to church.

Trypraying is the result, a seven-day guide to prayer of which 840,000 copies have now been printed. It is also available online, and is being read by people across the UK, America, Australia, New Zealand and the Czech Republic.

David (73) said: “I’m left totally bewildered that this idea could have grown so much. Edinburgh is the mothership but it is across the whole of Scotland and going around the world and people continue to give the money to put it out into public spaces.

“In America people are keen to develop this and we have someone working on it fulltime. We are making connections in Miami, Seattle, San Diego, so it’s poised and I think it is going to be huge. I think America needs this.

“There have been a few prophetic events. I was in the design studio as the first edition needed redoing when the designer’s eyes suddenly filled with tears and she told me she thought the project was huge. I thought it was just a booklet but she was seeing that it was more. Then a couple of weeks later a similar thing happened when another lady said she thought it was for all nations. The reach is staggering.

“We have so many individual stories of people who have seen the advert, got the booklet, worked through it and their lives have changed as a consequence – and that is the thing that keeps it alive in my opinion and it changes people’s lives.”

He explained that a member of one church had been talking to a man on the phone. He was struggling with life and it was suggested he try praying. David said: “At the exact moment a bus went by with our advert on it and he ended up becoming a Christian.”

The A6 size booklet is 48 pages and is designed to be easy to carry in a bag or a pocket. It is a seven-day programme each with a theme and a story of answered prayer. David concluded: “There’s also an ‘Honest to God’ prayer you can use which unwraps the idea of the spirit coming into your life.

“One man put the booklet on his coffee table and every day it seemed to get closer to him. He eventually read it and looked up to the ceiling and said ‘hello’. He was later baptised in the Firth of Forth – only the brave do that.”