The cover of Alex Preston's second novel, The Revelations, shows four cool dudes walking across a bridge in London.

They are two men and two women, each of whom exudes the kind of air one associates with city slickers, casting long shadows and striding with confident purpose, slim as champagne flutes, sexy and superficial. It is, as Preston acknowledges, a regrettable misrepresentation of his novel's content. "You have picked a scab that I let heal over," he says ruefully.

Preston is 33 years old and married with two young children. He is also bespectacled, balding and wearing a Queens Park Rangers scarf. The Revelations has just come out and, sitting in an antiseptic room in his Bloomsbury-based publishers, he is already smarting from a review which described it as a satire and an interview in the Evening Standard which insisted it was about "young bankers trying to find faith". That, suggests Preston, is as flagrant a breach of the Trades Description Act as it's possible to make.

"It just isn't about that. I think I wrote a book about the City [his debut novel, This Bleeding City] and I think that within and without it that's what they think this one is about. It just isn't to me. It's about four young people who are looking for a way of finding themselves in this alienating, dog-eat-dog world and being drawn to this religious movement."

The movement to which he refers is called the Course, which bears no small resemblance to the Alpha Course, a church within the Church of England, whose members are prone to visitations and speak in tongues. Since its foundation in the 1990s at Holy Trinity Church, Brompton, it has proved immensely popular and influential, to such an extent that the established church has little alternative but to tolerate it.

With Nicky Gumbel, a charismatic Anglican priest, at its head, the Alpha Course offers a seductive outlet for those who have come to feel that there must be more to life than what they're daily dealing with. Not only that, says Preston, "it is a ready-formed social environment for people who don't have one." Whereas churches such as the one he intermittently attends attract congregations you could count on one hand, those such as Trinity regularly have to turn people away, and for not entirely spiritual or religious reasons.

"You meet people there you could not only marry," says Preston, "but who you could possibly work for as well. Also, it answers a lot of questions."

Alpha Course members, like those who join the Course in The Revelations, are required to believe in "the literal letter of the Bible as law". Homo-sexuality is a no-no, as is sex before marriage. Which seems somewhat contradictory if Preston's personal experience is anything to go by. As a student at Oxford, where he came under the spell of the poet and pundit Tom Paulin, he couldn't help but notice the preponderance of good-looking female students who were members. Suddenly, like killers on Death Row, rugby players, who hitherto may have thought Julian of Norwich was a fly half, found they had a spiritual side. Added to which, many people who attend the Alpha Course appear to be fabulously wealthy.

For a while Preston attended the Course himself, having been brought up in the Church of England and performed as a child in the Southern Cathedrals Choir.

A friend of his was going out with a guy who "sort of strong-armed" her into joining and he agreed to go along with her. He was fascinated. There was the music – The Revelations is the name of the band that performs in church – and the conspicuous lack of any doubt. But Preston's hoped-for philosophical discussions of the meaning of life and other thorny issues did not materialise.

Among the many things that surprised him was the way the Course is marketed, especially in London, where, he says, "it's everywhere". It did not accord with his own sceptical view of religion and its inbuilt evangelical dynamic.

Religion, it seems, is not what motivates Preston's quartet of questing friends; what they're looking for is an outlet for their frustrations and desires and anxieties, brought on by frenetic city living, the complexity of the modern world and hyperactive hormones. Only one of them, Marcus, works in the City. His wife Abby, far from the stereotypical, plastic babe, is large of thigh and heading towards middle-age corpulence.

Mouse – Preston's acknowledged alter ego – is a chunky librarian who lives on a houseboat and lusts unrequitedly after Lee while visiting a brothel masquerading as a massage parlour.

For her part, Lee has had more one-night stands than a groupie, memorial-ising her conquests by photographing their penises while they're asleep. Much drink is consumed and drugs are not unknown, Preston being of a generation that did not recognise marijuana as a drug.

It's enough to make a Wee Free have an apoplectic fit. None of it, however, says Preston is fanciful. As a teenager growing up in Worthing listening to Suede, he dreamed one day of living in the sprawling metropolis. "London," he says, "was always this great, glittering city. I love London but I also find it a very frightening place."

At university he was head-hunted and thereafter he worked in the City as an analyst and trader, spending long hours in a high-octane environment where few, we may fairly assume, gave much thought to the existence of God or pondered long over Pascal's wager. In 2010 he escaped, as all around him imploded. An admirer of Donna Tartt's The Secret History and JD Salinger's Franny And Zooey, his interest in what he calls "the joyful seriousness of late adolescence" is what inspired The Revelations.

Preston's Oxford was a far cry from that depicted in Evelyn Waugh's Brideshead Revisited. But what connects them is guilt. Tell young people they are not allowed to do something and they're bound to do it. In that regard nothing much changes. That may not be His message or the Alpha Course's, but it's Alex Preston's.

The Revelations is published by Faber, priced £12.99. Alex Preston is appearing at the Mitchell Library, Glasgow, at 12.30pm on March 17 as part of Aye Write! book festival. For tickets, priced £7-8, visit or call 0141 353 8000.