Mum used to say that it was about Rob and me getting experience of religion, being exposed to it so we could make up our own minds, and we believed her, at least until we had young children of our own. Then we understood it was really about giving Mum and Dad a brief respite from noisy kids every Sunday.

As a six year old, I hadn’t enjoyed Bushey & Oxhey Methodist Sunday School: one morning on the car journey there, in my apprehensive mood I pressed my offering – a brass threepenny bit – so hard into my leg that it left a clear impression of its portcullis on my thigh.

Three years later, Rickmansworth Crusader class was much more fun. The leaders were younger and jollier, the choruses we sang were short and lively, and I became good friends with some of the boys – more so when some of them turned up in my class in the first year of Watford Grammar.

Crusaders had fun activities. There was poddox, a simplified and speedier form of cricket – perhaps exclusive to Crusaders – where each wicket consisted of two stumps with one bail, and a bowler was posted at each end to lob the ball underarm in alternating directions. The batters wielded rounders bats: if you hit the ball you had to run, and there were no boundaries. The heavy bat could propel the small ball a long way across Scotsbridge playing field, and it wasn’t unusual to score eight or nine off a single hit. Poddox was a great way to spend a Friday evening in the summer.

There were excursions like the trip to see Cliff Richard (wow!) perform at a gospel concert, like the five-a-side football tournament. Most of all there were the summer Crusader camps, usually by the seaside.

The days were full of fun and games and new friendships: after dinner was a prayer meeting where, tired and happy, we were receptive to hearing about God’s love. Then an evening walk followed by late night cocoa, and the magic of sleeping under canvas. (Crusaders are still with us today, having rebranded as Urban Saints in 2007.)

The experience of feeling safe and happy away from home and family was magical and intoxicating. The night I returned home, after volunteering to do the washing up I told Mum and Dad that I had accepted Jesus into my heart. I meant it, and at the age of twelve I regarded myself as a Christian. I tried diligently to read the prescribed Bible passage every night, and to say my prayers.

Watford Grammar was not diverse: in my year of about 120 boys two were Jewish and one was Asian. There was also one Catholic in our class who was excused daily assembly, which included hymns and prayers: the rest were all of white Christian Protestant heritage. But that didn’t prevent seeds of doubt being sown.

Our Divinity master was Mr (later Dr) Raper, a scholarly but approachable man. When the class had got over sniggering at his name, he started teaching us about each different religion in turn. By the end of term, he had taken us through the basic principles of Hinduism, Islam, Buddhism, Judaism, Shinto and Sikhism, and offered objective comparisons with Christianity.

(Dr Raper was later to raise his head above the parapet during the pupil rebellion against a new school rule banning long hair in the summer of 1971. In a morning assembly he parsed the word education, arguing that education should bring pupils out rather than up. How many boys understood this coded message of support is unclear, but it wasn’t lost on the headmaster, Mr L K Turner – known to us as Trog. Raper had gone by the next term, and I still wonder whether he was firing a parting shot because he was already on his way, or if this incident encouraged the headmaster to move him on.)

My Christian faith should have led me to reject the other religions as simply wrong. But I regarded myself as rational, and this posed a dilemma. Having seen the contradictions in the beliefs and customs of the major religions set out so clearly, favouring one over the others seemed merely a tribal choice, like supporting a particular football team. They couldn’t all be right. But they could all be wrong: surely that was the only reasonable conclusion?

My faith was further shaken by my Scripture teacher the following year. Mr Lister, who for unknown reasons had the nickname “Fanny”, was terrifying. A thin, austere figure, he was probably in his sixties, although he appeared at least ninety to us: he had white hair and a white moustache, and was one of the handful of staff who persisted in wearing a gown. In my mind he was an older version of Bunter’s Mr Quelch.

Our Scripture lesson was first period on Thursday morning, which made for a restless Wednesday night. Lister would set us a passage of the Bible to learn – maybe fifteen or twenty verses – and set us a ten question test the following week. The passage would be from the Authorised Version, usually from the Old Testament, and full of obscure and difficult names. If there was any spiritual content, I never discerned it.

The pass mark for the test was (I think) 7/10, and you could get a detention for failing. Of course we all crammed the text into our heads on the way to school on Thursday morning, so it was all completely forgotten by the weekend. We shouldn’t blame God if some people dedicated to spreading His word are uninspiring or downright scary, but I felt my faith weakening again.

Science lessons also encouraged religious scepticism: physics and astronomy, chemistry and biology – especially natural selection – pointed to the origins of the universe, the Earth, and life having natural origins and could explain our world without envisaging a supreme creator.

The coup de grâce was administered at Crusaders when I was fourteen or fifteen, a trivial blow which proved decisive only because my commitment to Jesus was already wavering. One of the junior leaders, a fellow in his early twenties, told a story one Sunday afternoon: he had been with friends, on a road trip in the United States, when their car ran out of gas, and they pulled up at the side of the road. They prayed for God to help them, and soon a friendly motorist stopped and gave them enough gas to get them to the next filling station.

This story was offered as proof of God’s love, and the power of prayer. It seemed absurd that His priority, with so much pain and suffering in the world, would be to deliver these young Englishmen from this annoying inconvenience. Of course this was just one man’s daft story, but years of growing scepticism welled up into a wholesale rejection of Christianity, and I stopped attending Crusaders. The decision may also have been encouraged by a wish to reclaim my Sunday afternoons.

I embraced atheism with the certainty of youth, and for a while adopted an aggressively anti-religious stance. This has softened over the years: I have met many kind and thoughtful people for whom faith clearly provided support and inspiration. Christ’s teachings are wonderful, but I don’t believe in him as the Son of God. I certainly dislike the angry modern strain of atheism which carries hints of the zealotry and intolerance which, ironically, characterise the nastiest aspects of some faiths.

A friend of mine is a lifelong Christian, who was once told by an associate that his faith was misguided, false and selfish. What must that have felt like? Imagine having a fragile ornament in your house, which you love and think beautiful. Then a guest comes to your house and says “I’ve done you a favour, I smashed that hideous ornament of yours.” What right did he have to do that?

My friend’s experience set me thinking about Mr Raper. He hadn’t, as far as I know, set out to turn us into atheists, but he did provide a framework which encouraged us to question our beliefs. Had the outcome been positive for me? Had I acquired truth at the cost of faith and a large portion of hope? Would I have been happier, or a better person, had I remained in that apparent fool’s paradise?

Pascal’s Wager points out that the cost of believing in God if there is none might be some wasted effort in adjusting one’s lifestyle and in attending church – while the cost of not believing in God if He does exist could be eternal damnation. Pascal concluded that it was rational for a doubter to behave as if there was a God.

In this spirit, I reserve the right to allow emotion to override reason, and to be born again late in life. But God, please could you allow me a bit of notice?