Each to their own, and all that, but I do occasionally enjoy challenging those who profess to have not one iota of religious belief. Nothing too heavy, you understand, as serious theology is quite beyond me. And I’m certainly not evangelising; often as not I’m just trying to keep a conversation ticking over. I restrict myself to a single aphorism, which goes like this: there are no atheists in a penalty shootout. I contend that most fans of the teams involved engage in something approximating prayer. The only exception, generally, will be the fans behind the goal who support the team whose goalkeeper is attempting to save the penalty about to be taken. As the player prepares to strike the ball, these fans may well pause their prayers to make hostile noises and obscene hand gestures in an attempt to put the penalty taker off. But by the time a player on their team is preparing to take the next penalty, they will silently resume praying.

This aphorism began life in the context not of sport, but war – although nobody seems sure which one. I thought the contention that there were no atheists in foxholes was first expressed at the time of Vietnam, but it turns out there are examples of its use in the second world war and, albeit referencing the trenches rather than a foxhole, in the first world war. The same idea was alive and kicking in the previous century too, when sinking ships were cited as a good place for faith-testing. Before that, I suppose the idea that there wasn’t some deity in charge of things was thought too absurd to merit challenge.

This all came to mind during the making of a series called My Life at Christmas for BBC One, which, I should point out, is a much cheerier watch than the above implies. In each show, I spend an hour talking to a well-known person – or persons, in the case of Martin and Shirlie Kemp – about what Christmas means to them. I was worried it might come across as a bit, well, cheesy, but once I had reluctantly caved in to the producer’s demands that I wear a Christmas jumper, I decided to just embrace the idea. I’m good like that.

And I’m so glad I did, because it turns out that getting people to reflect on the Christmases of their life is a remarkably efficient way of getting to the heart of them. Childhood and adulthood; home and professional life; hopes and dreams; joy and despair; success and failure. It’s all there. Religious belief – or lack thereof – is part of their stories, too. The champion dancer Oti Mabuse talks of church being a sanctuary for her when she was a kid growing up in Pretoria. Martin Kemp professes no faith, but nods when I invite him to try my aphorism on for size. He concedes he resorted to prayer when brain tumours put his life in danger. Shirlie, who was eventually confirmed as a Christian when she was 60, found herself in a hospital chapel praying angrily – as she put it – for Martin’s recovery.

John Simpson, foreign correspondent for nearly 60 of his 79 years, found solace, if not conviction, in Christianity. But this was long after he survived torture and a mock execution at the hands of Christian militia in Lebanon in 1982. In an exchange we haven’t used in Sunday’s programme, I asked him if, as the trigger was about to be pulled, he prayed. He said he didn’t. Neither did he thank God for salvation when the gun barrel proved to be empty. So, for John, this was no penalty shootout/foxhole/trench/sinking ship moment.

I asked him if, 40 years on, anything had changed; whether if, perish the thought, he was facing execution again, he would turn to prayer. He said he probably would. I suggested he probably shouldn’t. If not praying worked last time, why take the risk? “Never change a winning formula” would be my advice.

My Life at Christmas continues this Sunday on BBC One. All three programmes will be available on iPlayer before Christmas.