So what do they really believe?

Chicago, USA - So what exactly do Jews believe? Or Muslims? Or, for that matter, Christians, Buddhists and Druids?

And please explain each in 100 pages or so.

Trying to distill any belief to primal elements is perilous given the millions of faithful worldwide, some of whom can't agree on the shape of the faith they share.

But a series of slim, soft-cover, pocket-sized books is walking down that thorny path with 10 topics published so far and another two in the wings.

The "What Do We Believe" series from Britain's Granta Publishing, part of which is sold in North America by New York's Walker & Company, was conceived by editor George Miller, who was in New York City at the time of the Sept 11, 2001 attacks.

But while that event probably played some part in the origin of the series, he says, it was not conceived out of fear of the unknown "but a realization that the less we understood about other faiths, and the less we were able to distinguish what others believe from what we merely think they believe, the greater the scope for mutual misunderstanding, hostility and violence."

"We didn't necessarily expect to change the world, but we certainly hope that the books help inform the debate, and raise the quality of the debate," he told Reuters by e-mail from Europe. "One of the most encouraging signs of success is that translation rights have been bought in at least half a dozen languages."

As to the task involved, Miller said he conceived the "Very Short Introduction" series when he worked at Oxford University Press -- a project that now has dozens of titles with concise explanations for everything from "The Renaissance" to philosopher John Locke.

"From the start, the brief to the authors was to explain rather than seek to convert. We told them that we didn't want neatly packaged solutions to difficult issues where none existed," Miller said.

"Where a religion had a particular dilemma to face, we wanted that to be covered honestly. We wanted the books to avoid giving the impression that religions did not have dark chapters in their histories, but at the same time we didn't want them to focus solely on the problematic areas," he added.

He credits Belfast-born Tony Morris who became the editor of the series early on, and who, as a practicing Buddhist, wrote the "What Do Buddhists Believe" book in the series.

"Tony and I worked a great deal with the authors both at the proposal stage and when the books were in development to ensure that they were balanced, approachable and covered the questions that newcomers genuinely have when they encounter an unfamiliar faith," Miller said.

"Some of the books probably went through four or five rounds of detailed editing to make sure that they fulfilled the aims we had set. I think it would be fair to say that all the authors we selected to write for us were chosen in part for their interest in dialogue with other faiths as well as their abilities as communicators."

The other titles in the Granta series are Nicholas Campion's "What Do Astrologers Believe?"; Malcolm Guite's "What Do Christians Believe?"; Philip Carr-Gomm's "What Do Druids Believe?"; Richard Appignanesi's "What Do Existentialists Believe?"; Joe Smith's, "What Do Greens Believe?"; Edward Kessler's "What Do Jews Believe?"; Ziauddin Sardar's "What Do Muslims Believe?"; Graham Harvey's "What Do Pagans Believe?" and Colin Shindler's "What Do Zionists Believe?"

Yet to come are issues on Hindus and Catholics.

Miller said the best selling titles have been the ones on major religions "but we felt it was important to represent other belief systems, too, to try to give some sense of the diversity of contemporary belief."

George Gibson, publisher of Walker in New York, said his company has released the titles on Jews and Muslims to the North American market and will issue those on Christians and Buddhists in 2008.

"We've gotten requests from our sales people that we do a book on Mormons," a faith gaining new interest in the United States with the presidential bid of Mitt Romney, a member of the Church of Jesus Christ of the Latter-day Saints.

"They are wonderfully compact but contain an enormous amount of information," Gibson said of the books.

Each carries a glossary and a guide to further reading. The book on Christianity, for example, refers readers to several books, including Augustine's "Confessions" -- "written in 398 and still fresh."