Richard Dawkins rarely raises his voice. He speaks in a melodious, fatherly tone that undulates between wonder and exasperation. But, make no mistake, he is annoyed – and not by any priest or imam but by a fellow Oxford-educated member of the English establishment classes.

“I am deeply pessimistic,” he says, reflecting on British prime minister Boris Johnson’s latest manoeuvrings. “I think the Brexiteers started out by having a belief it would be a good thing; it has become a religion now. It has become a faith. It has become a creed... It has become like religious zeal. They are determined to get Brexit even if they destroy the country, and Scotland breaks away in the process. It’s a form of madness.”

A couple of hours after speaking to The Irish Times, he is on Twitter urging his 2.8 million followers to “STOP THE COUP” – complete with angry capital letters – by joining him at a public protest against the proroguing of parliament. “DEFEND OUR PARLIAMENTARY DEMOCRACY against dictatorship by an ‘Over-promoted rubber bath toy’ (copyright Hugh Grant),” he tweets.

You might almost forget Dawkins is in the middle of a publicity circuit for his latest book Outgrowing God: A Beginner’s Guide to Atheism. But he brings to the Brexit debate the same sort of rigid reasoning with which he is synonymous in the religious world.

Just weeks before the referendum in June 2016, he spelt out his thinking in Prospect Magazine, explaining that his own answer to the question of whether to leave or remain was: “How should I know? I don’t have a degree in economics. Or history. How dare you entrust such an important decision to ignoramuses like me?”

Just as Michael Gove – another Oxford man – was pooh-poohing the role of experts, Dawkins was defending them. “You want your surgeon to know anatomy. You want the pilot of your airliner to have cerebral knowledge and cerebellar skills honed by painstakingly many flying hours… Am I being elitist? Yes of course I am, and why not?”

I made inquiries to see whether I could become an Irish citizen. I gather I can’t because I can’t produce an Irish grandparent, much to my regret. I would love to become an Irish citizen

The evolutionary biologist deploys the same sort of debating tactics on Brexit as he has done on religion. As with those who say Jesus is the son of God, political grandstanders are told to provide proof. Where, he asks, is the evidence that Britain will be better off outside of the European Union?

He calls out inconsistency in reasoning, and he is not afraid to needle his opponents. Suggesting that a better intellectual life can be had outside of England, he has floated the idea of moving elsewhere – proposing Ireland a couple of years ago. “I made inquiries to see whether I could become an Irish citizen,” he says. “I gather I can’t because I can’t produce an Irish grandparent, much to my regret. I would love to become an Irish citizen.”

He has plenty of Irish fans anyway who’d welcome the move. When he visited Dublin a few years after releasing The God Delusion he sold-out the National Concert Hall and got a standing ovation to boot – a rather mechanical gesture, one might say, from a room full of supposed free-thinkers. For full disclosure (since Dawkins is one of those cultural figures it’s impossible not to have an opinion on), I have read several of his works and have admired and have often been persuaded by his writing without ever falling in love with it.

There are other atheist authors who have written with more nuance and insight about the journey to unbelief, and whether or not it really counts as a destination. Richard Holloway, Philip Kitcher, and the recently deceased Bryan Magee come to mind. (Why is it mostly men who are prominent in the God debate? Answers on a postcard.)

Both Dawkins and Raymond Tallis have made the argument that to call yourself agnostic you must believe there is a real, quantifiable chance of there being a God, and not just a vague, theoretical possibility. Yet, for some reason, it’s the more temperate author Tallis who I credit for my own decision some years ago to lapse from agnosticism into atheism.

That all said, Dawkins’ new book is perhaps his most likeable. It’s written for a younger age group – “my target audience is about 15 years old” – and for that reason he is less strident in his approach. Compared to previous form, he makes fewer statements and asks more questions. How do believers decide which God to chose? If you were Abraham could you ever forgive God? Was the God of the Old Testament a racist?

The tactic is deliberate, he says, to mimic the questions a curious child might have. “And I’ve taken care not to answer the questions but to leave it up to the reader to do so. I am extremely anxious since I’m writing for a younger audience not to be seen as indoctrinating because we criticise churches, religious institutions, for indoctrinating children... I want to encourage thought by the reader.”

The book’s release date will ensure it sells, ironically, as a Christmas stocking filler. “I tried it out on a 10 year old who liked it,” the 78-year-old says, “but I like to think I’ve written it in such a way it would be appealing to all ages as well”. There is plenty of ammunition here for precocious youngsters to cause havoc in RE class, and the thought of an army of Dawkins acolytes in short trousers will be enough to horrify many a bishop.

However, the book is open to the same sort of criticism that was levelled against The God Delusion, in particular by giving a skewed account of religion’s contribution to civilisation, and also by undervaluing the role of religious thinkers in trying to answer questions beyond the reach of science.

To the second charge, he replies: “There are questions that science cannot answer, maybe can never answer. But what on earth makes you think religion can?”

He adds: “The track record of science, if you look at the history of science, is that one-by-one these questions fall – one-by-one science answers them.”

What about a question such as: “What makes human beings valuable?” A few years ago Dawkins controversially weighed into the debate about abortion and Down Syndrome. He was forced to apologise over some of his language but stood over his stance, saying: “Given a free choice of having an early abortion or deliberately bringing a Down child into the world, I think the moral and sensible choice would be to abort.”

I think nationalism is a major force for evil… ‘My country right or wrong’, that kind of thing, is a major flaw in humanity

Christianity has a ready-made answer for why human life is valuable. How does an atheist explain it? “You are as valuable as you think you are,” replies Dawkins. “Science can’t answer a question like, ‘Is human life valuable?’ That’s a value judgement and that value judgment remains whether you’re religious or not.

“I think the exceptionalism of humanity needs examining,” he continues. “There are many respects in which humans are indeed exceptional. We are the only species that has language, that has culture – at least has an advanced culture – that can write, learn from its history and so on.

“We are a very unique species. That is valuable. That is an immense plus when asking a question about human value. On the other hand, we are evolved animals. We are African apes. We branched off from the other animals and the other African apes rather recently. So we need to hold both those in our head at the same time.”

As for “Why are we here?” or “What’s the meaning of life?”, Dawkins replies: “Insofar as we can ever answer those very deep questions about ultimate existence, it is only science that can do that, but personally we have our own meanings.”

He lists various things that give meaning to his life: “Human love… poetry… literature… beautiful scenery…” He also feels “a strong sense of purpose as an educator” – and clearly as a campaigner too. As one of the so-called horsemen of atheism, he is credited with generating a more honest or, depending on your view, unhealthy dialogue between religious believers and non-believers. But is religion the greatest threat to humanity today? Is it enemy number one?

“No, I don’t think so. I think nowadays we have to mention climate change. We could be heading for real disaster... So that might be number one.

“Religion is an important negative force but then any kind of ideology – nationalism, America first… Brazil – I mean, allowing the Brazilian forests to burn and then accusing the rest of the world of interference in our national sovereignty. The lungs of the world in that gigantic forest belong to the world.

“So I think nationalism is a major force for evil… ‘My country right or wrong’, that kind of thing, is a major flaw in humanity and religionism is just another one.”

Outgrowing God: A Beginner’s Guide to Atheism by Richard Dawkins (Bantam Press) is released on September 19th, priced £14.99.