A. C. Grayling is not an atheist. Nor is he an a-goblinist, an a-fairiest, or an a-pixieist. He recognises no label that describes his lack of belief in the Loch Ness Monster, or his scepticism about the existence of the Tooth Fairy. "Terms like atheist", he laments, "are meaningless; they’re usually employed by theists to collectivise those who disagree with them." Grayling, the current Professor of Philosophy at Birkbeck, University of London and Fellow of both the Royal Society of Literature and of the Arts, much prefers the term "free-thinker". "I did once describe myself as a naturalist, as opposed to a super-naturalist, but people kept on getting it confused with naturist and began casting aspersions on what I did with my weekends."

Interviews with Professor Grayling often begin with categorisations: the public intellectual, the lion-maned philosopher, the outspoken critic of religion. I began by asking him about the source of that final description. Did his lack of faith appear to him, so to speak, as an epiphany, or did he feel, to paraphrase Pascal’s Wager, "so made as not to believe"?

"I certainly wasn’t born a non-believer, but I think I can trace its starting point." As a young pupil at an Anglican boys’ boarding school, each morning Grayling would find himself being marched along to chapel for prayers. "None of us used to take any notice, we’d usually spend most of the time flicking scrunched up balls of paper at each another. But then one day we had a new chaplain who, rather unlike the meek gentleman he had replaced, read out the collect of the day by affecting all these revivalist, evangelical hollers and shouts." The stress this new preacher placed, in particular, upon the vowels of the word ‘inspiration’ seemed to grab the attention of the young Grayling. "By the sheerest coincidence, just the preceding week I’d been reading about the Greek view of inspiration and how the muses supposedly breathed into you the poetry, like they did Homer. So I approached this chaplain and said, ‘Inspiration, that’s a very interesting concept, can you give me something to read about this Christianity business?’ He did and as a studious little chap I went off and read it." Upon his return, Grayling proudly announced that he had completed his reading, but he had a query: "My question was simple, ‘how can you possibly believe all this stuff?’" The response was a simply one. "He said to me that ‘every morning I wake up and I pray, "Oh Lord, I believe, but help thou mine unbelief,"’ to which I replied, ‘Ah, so you don’t believe this stuff either!’"

Professor Grayling was a colonial baby. Having been born in Zambia, a colony in which he says the only two entertainments were adultery and golf, he spent much of his childhood in a curious local library. "It consisted mostly of books that had been left behind by British expats, most of whom had died of awful tropical diseases. But amongst the books was a complete set of Plato’s dialogues, and at the age of twelve I very randomly picked out the Charmides. I was bowled over by it, I thought it was absolutely wonderful." Soon Grayling would return to Britain and to the University of Sussex and later Magdalen College, Oxford to read philosophy.

Today, Grayling is the author of a library of books and countless articles, ranging from the theory of knowledge to the impact of faith schools on social cohesion. But he remains best known for his anti-religious writings, and doesn’t seem too perturbed by that. I asked him whether he ever becomes frustrated by the seemingly endless debate between the faithful and the faithless. "The trick is not to get angry with the individual, but rather with the idea. Whenever I’m speaking at a conference, I often find myself placed on a panel of some sort next to a Catholic, a Muslim, a Jew and an Anglican. Combined, these people represent about eight per cent of the worshipping population of this country. I’m there, ostensibly, to represent the atheist, secular, and humanist tradition. I often tell the audience that the only reason there’s only one of me, and four of them, is that none of them can get along with each other."

Grayling reclines and smiles at this. For a renowned academic he seems surprisingly laid-back – almost avuncular. And yet, behind those professorial rimless glasses there lies a serious and reflective philosopher; the self-deprecation may be disarming but that’s only because, more often than not, it’s followed up by some profound, aphoristic quip. And what about the corollary, what makes A.C. Grayling happy? "I believe in the good life – and by ‘good’ I don’t mean to sound like a goody-two-shoes. After all there as many ‘good lives’ as there are people to live them. But for me, having fun, forming productive relationships, and searching for meaning in life are the most important parts to our great enterprise. Our lives are less than a thousand months long, and we spend at least a third of that in the shower or in Tesco. We must make the most it."

Grayling is a contented soul, but he worries for those who waste their lives seeking to make the right propitiations, and to the right God, in the hope that the party of life will continue long after the lights have been switched off. "The ‘good’ is too various for anyone to offer a defining vision of it, but that, I suppose, is the great beauty of secularism. A pluralist, secularist society offers us freedom of choice and has replaced the totality of the religious and absolutist states of the past. To my mind, it’s the only form of society that offers us the chance of true individual happiness."