"Prominent, sought after scholars will address the theme of the convention at large," they add. "The session is both relevant and meaningful to Islam in North America."

Since Sayyid Syeed, a longtime leader with ISNA who focuses on building the organization's interfaith ties, invited Warren to speak during a White House gathering they attended last year, the Southern California pastor has refrained from making any public comments regarding the invitation.

But Syeed told The Indianapolis Star, the largest newspaper in Indiana, where ISNA is based, that Warren "realizes that it is equally critical for him to work with people of other faiths."

The Islamic Society, an umbrella association for tens of thousands of Muslims, has reportedly worked for years to persuade leaders of other faiths to attend its convention - a massive family reunion that draws about 30,000 people. The Islamic Society says the U.S. Agency for International Development (USAID), U.S. Department of State, U.S. Department of Homeland Security, and the U.S. Department of Justice will be among the agencies represented during a session Saturday on "Government Outreach to the Muslim American Community."

"Some problems are so big you have to team tackle them," evangelical megachurch pastor Rick Warren addressed the annual convention of the Islamic Society of North America (ISNA). Warren said Muslims and Christians should be partners in working to end what he calls "the five global giants" of war, poverty, corruption, disease, and illiteracy.

A Southern Baptist, Warren has a record of upsetting fellow Christian conservatives by calling old-guard evangelical activists too partisan and narrowly focused. Ahead of his speech Saturday, bloggers who follow Warren had already denounced his appearance at the convention as cozying up to extremists.

"It's easier to be an extremist of any kind because then you only have one group of people mad at you," he said. "But if you actually try to build relationships - like invite an evangelical pastor to your gathering - you'll get criticized for it. So will I."

In his speech, Warren also urged Muslims and Christians to speak out against stereotyping of any group and to respect each other even while disagreeing. Addressing Muslims who "have been in America for many generations now," he urged them to help "the newcomers learn what it means to be American."

That would make them more numerous than Buddhists (of which there are 144,500, according to the 2001 census) and almost as numerous as Jews (259,000) - and it doesn't even allow for the growing tribe of unofficial, instinctive pagans such as my friend Cath, who planned to celebrate the summer solstice in the early hours yesterday by "going out into the garden at dawn and just tuning in". At Stonehenge at least 30,000 people were expected to watch the sun rise in the company of the druids who see themselves as practising the ancient faith of pre-Christian Britain. For them, the sun is symbolic of one aspect of the "universal force which flows through the world and which can be encouraged to flow through us", according to Philip Carr-Gomm, founder of the Order of Bards, Ovates and Druids and author of the new Book of English Magic. The druids are only a small part of modern paganism, which encompasses a bewildering number of traditions or "paths", but central to them all is this idea of a divine force inherent in nature. It is an individualistic faith that encourages each person to respond in their own way, so you don't have to be a druid, or belong to any kind of order at all.

"Everyone's a pagan now." Not quite, maybe, but the rise has been dramatic. The census in 2001 recorded 40,000 pagans, but the true figure may be higher. "Pagans don't like telling the government what they're up to," says Ellis.

The Pagan Federation's membership list includes druids as well as wiccans, practising modern witchcraft; shamans, engaging with the spirits of the land; and heathens, worshipping the gods of the north European tribes (including Thor). But then there are the neopagans such as Bantu, always visible at environmental protests, who wouldn't think of belonging to any kind of federation and who pursue a rainbow of revived, recreated or invented beliefs with nature at their heart.

All you have to believe to be a pagan, according to the federation, is that each of us has the right to follow our own path (as long as it harms no-one else); that the higher power (or powers) exists; and that nature is to be venerated. If you asked everyone in Britain if they agreed with those three statements, millions would put their hands up. At its loosest, paganism is beginning to look like our new national faith.