RICHMOND -- In this steamy Southern city, two men have divided up the world. Demographers David Barrett and Todd Johnson have partitioned the globe into 238 countries, 33,800 denominations and 13,600 groups of people speaking 12,500 languages for their World Christian Encyclopedia.
Now they want to put the mammoth amount of information that details global Christianity and sums up other religions on the World Wide Web and in a CD-ROM.
"There used to be all sorts of disparaging things said about large numbers; that they mean nothing or they are exaggerated," Mr. Barrett says. "You don't get that kind of opposition now. You do not ask how a billionaire knows he's a billionaire."
The encyclopedia, which comes in two volumes, includes 1,699 pages of tables, graphs and maps summing up facts on religion. What separates the encyclopedia from other compilations is its reliance on a massive network of churches, agencies and missionaries that document the real numbers of Christians in isolated parts of the world.
According to that research, Christianity is the most universal religion. The 2 billion Christians constitute 33 percent of the world's population and have representation in every country. But Baha'is (218 countries) and Muslims (204 countries) aren't far behind.
The world's atheists and agnostics number 918 million, or 15.2 percent of the population. The bulk of them (500 million) live in China.
"Everyone has underestimated the magnitude of what we are talking about," said Mr. Barrett, who along with Mr. Johnson has gathered data since 1968 for several editions of the encyclopedia first published in 1982.
They still are collecting information. Mr. Johnson left last weekend for a six-month research trip to Singapore. In January, the two men will move their research facilities from a Presbyterian church in Richmond to Gordon Conwell Theological Seminary near Boston.
As civilizations clash, religion and its role are as vital as ever. Birthrates are important, which is why an Islamic growth rate of 2.13 percent bodes well for that religion. Christianity is growing at 1.36 percent.
The two researchers said Islam's growth owes a lot to high birthrates in the Middle Eastern and South Asian countries where the bulk of its adherents live.
The researchers went to great pain to document martyrdoms, especially those of the 70 million Christians over the past 20 centuries. The worst single massacre was China's Great Proletarian Revolution of 1966 and 1967, in which 22 million people died, 3 million of them Christian. It was the most systematic attempt by a single nation to wipe out Christianity.
"In one place," Mr. Barrett says, "they lined up 600 Roman Catholic priests. And they shot them all."
Over 20 millennia, however, that number pales in comparison with the 37.4 million Orthodox Christians who top the list of martyrs. Most of them died under communism. The next highest category are the 12.4 million Nestorian Christians in Central Asia and China who died in the 13th and 14th centuries at the hands of Mongols Genghis Khan and Tamerlane.
More than half of all Christian martyrdoms occurred in the 20th century. The World Christian Encyclopedia lists 112 methods, including atheistic Croats tossing Catholic priests into icy rivers in the 1970s and the crucifixions of Japanese Catholics during the 17th century Tokugawa period.
Other religions also have martyrs. Islam claims 80 million; Hinduism, 20 million; Buddhism, 10 million; Judaism, 9 million; Sikhism, 2 million; and Baha'is, 1 million.
"Baha'is been savagely persecuted in Iran over the past 30 years," Mr. Barrett says. "They have been slaughtered right, left and center."
Muslims consider anyone who dies in battle to be a martyr; other religions count only those who are slain because of hostility toward their beliefs.
Ihsan Bagby, a University of Kentucky professor who completed a census of American Muslims in 2001, says the 80 million figure is "make believe." He added, "Muslims do not keep track of things like that. There is no global consciousness of people martyred."
Mr. Barrett, a former aerodynamicist with the British government, became interested in statistics during his 34 years as an Anglican missionary in Africa. Taking seriously an admonition by Prior Roger Schutz of the Taize Community in Cluny, France — "Statistics are signs from God" — he began a comprehensive survey of all branches of global Christianity in 1962.
"David traveled to almost every country," Mr. Johnson says, except China. Nor has he been to Antarctica.
During the 1960s and 1970s, Mr. Barrett — who reads Latin and speaks English, French, Swahili and Luo (an upper Nile language) — began amassing a network of informants in church agencies, denominations, Bible societies and mission groups around the world.
He discovered that cities like Singapore, Geneva and London were "research nodes" where collections of people and material came together.
The first edition of the World Christian Encyclopedia, begun in 1968, was to have taken only three years. It took 12 to produce and was issued in 1982. It has been heavily quoted from ever since.
A second edition, containing two volumes at $295 a set, came out in 2000. Mr. Barrett enlisted Mr. Johnson, formerly a missionary in Thailand, and George Kurian, founder and president of the Society of Encyclopedists, to help.
A few surprising statistics have emerged.
One category, the world's 400 million independent Christians, who said they believed but didn't belong to a denomination, had not been counted. Researchers searched everywhere from 100,000 independent churches listed in the U.S. Yellow Pages to tribal contacts in Africa.
Of Antarctica's 5,000 part- and full-time residents, 3,400 of them are Christian and 400 of them are charismatic Christians.
The researchers were surprised by a "massive" defection from Christianity during the 20th century because of world communism, secularism and materialism.
Christianity expanded greatly from 1815 to 1914, but "no Christian strategist in 1900 had envisaged such a massive rate of defection from Christianity from its 19th-century heartlands" in Europe and Russia, they wrote. This was mitigated somewhat by the breakup of the Soviet Union in the early 1990s.