Comedian Matt Lucas has written a book of his life with one chapter for every letter of the alphabet. Picking it up, I expect it to reflect the humour that made him and co-star David Walliams famous. O for over the top, S for sneers, B for blacking up, and C for chav jokes, perhaps.

But the book, though funny, is much more than a warmed-up episode of the show. And the man I speak to on the phone is pensive, softly spoken and reserved.

Perhaps he’s cautious because I am a journalist, but I get none of the frivolity I expected from the man who has maintained that his own “fatness” and “baldness” are funny. Then again, Little Britain was 10 years ago and Lucas has said that society and humour have moved on since then.

We start with what I think are gentle questions about his Jewish background. He’s not in the mood for superficial answers.

“I think it would be hypocritical to feign faith,” he says. “If you don’t have it, you don’t have it. I just don’t believe in God”.

Lucas grew up in north west London, his parents came from traditional Orthodox families but joined Edgware and District Reform Synagogue when they got married. Family life centred around the shul, where his mother was the assistant secretary for more than 20 years. At EDRS he developed a sense of community and made many friends. “It was something I really connected with. A lot of my friendships came through that and are still going strong,” he tells me.

While Lucas remains resolute in the belief that God does not exist, he is keen to point out that he means no offence to JC readers who do believe. It strikes me as odd that someone who created characters like Vicky Pollard, the council estate mum in a tracksuit, cares at all about what people think.

He stresses that he does not want to be seen as judging anyone else’s beliefs. “I don’t look down on people who do believe, but I can’t pretend to feel something when I don’t feel it. I don’t want to be a hypocrite and I don’t want to be fake.”

In Little Me, he writes about a visit to Ethiopia with Comic Relief where he met a man wasting away from Aids. The image of the man in a tiny hut with a picture of Jesus on wall led Lucas to the assumption that if God did exist he “was not very nice,” or that He existed but “was not good at it, like Aston Villa.”

Did he think that the way bad things happen to good people is to blame for his steadfast attitude to a question that no one really knows the answer to?

“I don’t know,” he says taking a pause to think.

Certainly, his book details many bad things that he’s had to contend with, including his alopecia as a child, his father being sent to prison for fraud, his parents’ divorce and his ex-husband, the “love of his life” Kevin McGee, committing suicide in 2009, after the pair divorced.

“Until my early 20s I was very resolute that there was a God. I believed in him. I think if you are very religious and bad things happen to you, you might question ‘why?’ in way you wouldn’t if you don’t believe in God.”

So, with those different chapters in his book, one for each letter of the alphabet. J is for, you guessed it, Jewish.

He writes about his two starkly different barmitzvah parties. One held by his mum and one, a much “humbler” affair, held by his dad at a run-down community centre. “My school friends started to appear in their expensive suits. They were doubtless as confused as I was. There was no silver service, no Ray McVay and his Big Band,” he writes. “My barmitzvah party was thrown with great love by my father and step-mother but it was so different to anything else I had experienced , and I was not prepared for it. To my eternal shame, I was embarrassed by its humbleness. Looking back, I’ve got a horrible feeling I showed little gratitude.”

He went to Haberdashers’ Aske’s Boys’ School, a breeding ground for Jewish comedians including David Baddiel, Ashley Blaker and Sacha Baron Cohen. Lucas writes fondly of Rabbi Willschanski, who visited the school regularly: “a jolly old soul who spoke with a thick Yiddish accent, played the fiddle and told jokes about Jewish people eating too much.”

In K, the chapter about McGee, there are few words, but a gallery of pictures of the two of them together. He politely declines expanding on their relationship in any detail so as not to appear he is using it as a tool for “self-promotion.

“Everything that I want to say about grief and Kevin is in the book and I say it much better than I can here.

“I think grief is a part of many people’s lives so there is universality to it.

“The thing to remember when you’re going through the worst of it is to look around and realise at some point everyone has been through something similar and the world is still turning. One day you will feel better than you do now.”

Being gay and part of the Jewish community was never a problem for Lucas, 43, who describes his coming out experience in his 20s as positive, despite feeling “invisible” growing up.

“I was born in 1974, and when I was 14 or 15 they bought in the first anti-gay legislation for 100 years.

Section 28 banned the promotion of homosexuality in schools. It meant teachers were not able to acknowledge the existence of homosexuality out of fear of being seen to promote it.

“It was a strange time to think about trying to come out. But once I had spoken to the people close to me it felt OK and it wasn’t regarded as anything negative.

“I think you worry about coming out, but usually people have already figured it out themselves or they are not bothered about it.

“To anyone worried about coming out, I’d say don’t be, because it can be a positive experience.”

I felt sad for Lucas as I read the book. He dedicates a chapter to describing what an “idiot” he is and there is not a page without some sort of self-deprecation, be it about his physical appearance or career achievements.

He laughs for the first time during our interview when I ask if he thinks he could be kinder to himself?

“The other extreme is to think you’re wonderful simply because you are you, and that is an unattractive and unhealthy place to be.

“It is narcissism and I’d much rather be at the other end of the scale.”

When it comes to politics he “veers more to the left,” he says. He was against Brexit, although he is not uncritical of the European Union. When I ask him if he feels comfortable as a Jew on the left he is quick to correct me.

“I’m not on the left,” he asserts, nor is he “a Labour lovey,” but he is genuinely concerned about living in a time of “political extremes”.

“Complacency is the real enemy. I make no assumptions. Look at the political leaders around the world and we can see there are now clear routes for extremists that were not there 10 or 20 years ago. We have to be vigilant and aware and challenge people that come out with xenophobic things.” X for Xenophobia is a chapter of just three lines. I won’t spoil them.

Lucas, who says he wants to make a musical as his next project, belongs to more than one minority group — he is gay, Jewish and a Jewish supporter of Arsenal — but says he is not tribal, “unlike like British politics.

“I haven’t always voted for the same party. I don’t like to be tribal. The only tribe I don’t mind being a part of is Arsenal.”

Little Me: My Life from A-Z by Matt Lucas is published by Canongate Books (£20)