A.C.Grayling says his book…doesn’t attack religion, it’s a positive book, there’s nothing negative in it. People may think it’s against religion – but it isn’t.” But then he says, with a mischievous twinkle: “Of course, what would really help the book a lot in America is if somebody tries to shoot me.”

With any luck it shouldn’t come to that, but Grayling is almost certainly going to upset a lot of Christians, for what he has written is a secular bible. The Good Book mirrors the Bible in both form and language, and is, as its author says, “ambitious and hubristic – a distillation of the best that has been thought and said by people who’ve really experienced life, and thought about it”. Drawing on classical secular texts from east and west, Grayling has “done just what the Bible makers did with the sacred texts”, reworking them into a “great treasury of insight and consolation and inspiration and uplift and understanding in the great non-religious traditions of the world”. He has been working on his opus for several decades, and the result is an extravagantly erudite manifesto for rational thought…

Who does he think will read The Good Book? “Well, I’m hoping absolutely every human being on the planet.” He’s sure that a lot of people will wonder just who he thinks he is, to have written a bible, but doesn’t appear particularly troubled by this prospect. “The truth is that the book is very modestly done. My wife did give me a card,” he giggles, “that said, ‘I used to be an atheist until I realised I am God’. And I know that on Monty Pythonesque grounds there’s a good likelihood that in five centuries time I will be one, as a result of this.” He lets out another little chuckle. “But I certainly don’t feel like one now, that’s for sure.”

The little jokes and kindly bearing can make Grayling sound quite benignly jovial about religion at times, as he chuckles away about “men in dresses” and “believing in fairies at the bottom of the garden”, and throws out playfully mocking asides such as, “You can see we no longer really believe in God, because of all the CCTV cameras keeping watch on us.” But when I suggest that he sounds less enraged than amused by religion, he says quickly: “Well, it does make me angry, because it causes a great deal of harm and unhappiness…”

… We have to try to persuade society as a whole to recognise that religious groups are self-constituted interest groups; they exist to promote their point of view. Now, in a liberal democracy they have every right to do so. But they have no greater right than anybody else, any political party or Women’s Institute or trade union. But for historical reasons they have massively overinflated influence – faith-based schools, religious broadcasting, bishops in the House of Lords, the presence of religion at every public event. We’ve got to push it back to its right size.”

Atheists, according to Grayling, divide into three broad categories. There are those for whom this secular objection to the privileged status of religion in public life is the driving force of their concern. Then there are those, “like my chum Richard Dawkins”, who are principally concerned with the metaphysical question of God’s existence. “And I would certainly say there is an intrinsic problem about belief in falsehood.” In other words, even if a person’s faith did no harm to anybody, Grayling still wouldn’t like it. “But the third point is about our ethics – how we live, how we treat one another, what the good life is. And that’s the question that really concerns me the most.”

Exactly the same round robin of reflection I encountered and resolved when still a teenager. The atheist part came first and easiest. Studying materialist philosophy – especially as a dialectic, a mirror of physical processes in science – took a bit more work and brought an enormous amount of satisfaction in knowledge.

A study habit I’ve never lost and never will.