(RNS) About 300 years ago in the Delaware River valley, a group of Christian idealists banded together to create a family-based agricultural society that valued individuals equally, regardless of race, gender or religion.

In doing so, the Religious Society of Friends, or Quakers, essentially created America, according to syndicated columnist David Yount, author of the recently published book "How the Quakers Invented America."

"The liberty that Americans take for granted originated not in the minds of secular Enlightenment thinkers but from the application of the Quakers' Christian faith," writes Yount, himself a Quaker. As much as Quakers changed America, however, America changed Quakers, according to contemporary Friends.

And William Penn, who founded the Pennsylvania commonwealth, might be bewildered by the variety of people practicing his faith today.

Consider the following examples of contemporary Quakers:

-- Isabel Penraeth, 36, of Denver, a conservative who wears traditional Quaker garb and believes "Christ is the light of every person born in the world."

-- Valerie Brown, 51, of New Jersey, who is both a Friend and a Zen Buddhist. "The Quaker belief of seeing God in everyone certainly resonates with Buddhist principles," Brown says.

-- James Healton, pastor of the evangelical Friends Community Church in Sacramento, Calif., for 25 years, who dislikes fellow Quakers' "free and easy attitude to Christianity."

-- Pagan-Quakers Peter Bishop and Cat Chapin-Bishop, 47, of Western Massachusetts. "I thought you had to be Christian (to be a Quaker)," she said. "... Plenty of people disabused me of that notion."

-- Catherine Whitmire of Washington, a Quaker author who says the tradition's devotion to simplicity, integrity, peace and equality can unite contemporary Quakers.

"Friends over the centuries have gone in so many different directions, there's hardly anything but some history that ties them all together," said Bill Samuel, 59, who left Quakerism after 50 years because he couldn't find a Christian meeting near his home in Maryland.

In some ways, Quakerism itself is to blame for the variety of Friends it's bloomed.

Founded by George Fox in England during the 1640s, early Quakerism eschewed the creeds, sacraments and hierarchies of the established Christian churches. Instead, Quakers preached that the "inner light of God" avails itself to all. Instead of church services, many held "meetings" in which believers waited in expectant silence for the still small voice of the divine.

But with this radical trust in individual revelation, however, came the question of separating the truly God-inspired from the hobgoblins of human imagination.

Quakers past and present insist revelations are tested against the discernment of the community. But that leads to questions about what the community uses to gauge truth, said Quaker historian Thomas Hamm, of Indiana's Earlham College. Should it be Scripture? Quaker history? The leading of elders? The Holy Spirit?

"In a lot of cases, Friends want to try to avoid those kinds of discussions partly because they're afraid of the tensions they create,"

Hamm said. "Because if you think the essence of the faith is seeking after your own light, how could you possibly impose your light on someone else?"

The roughly 100,000 Quakers in the U.S. haven't entirely avoided those discussions, however, and Friends now split into four main branches. Three are explicitly Christian; the more liberal fourth branch is less emphatic about its Christian identity.

Across the board, Quakers embrace a variety of theologies and practices. About one-third of Quakers, for example, hold mostly silent, "unprogrammed" meetings each Sunday, meaning no music, sermon or liturgy.

The majority of Quakers belong to "pastoral" meetings or churches, which have assimilated by degrees into mainstream Protestant culture, with praise bands and pastors.

Liberal Quakers, who shade into pantheism and even atheism, say that early Quakers used the religious language of their time -- Christianity

-- to express their revelations. Quakers now "have more light" and can move past those revelations, they say.

On the other hand, Bible-believing evangelical Friends say some Quaker peculiarities, such as the lack of sacraments, should be jettisoned in order to reach potential converts.

Each side is exerting an almost gravitational pull toward the extremes, according to Friends.

"We're a small planet and we're circling two different suns," said Healton, the Sacramento preacher.

Robin Mohr, 39, a San Francisco Quaker, said the Quaker planet may be swinging away from "Quakerism-means-you-can-believe-what-you want" and back to a more Christ-centered orbit.

Mohr and others are using blogs to foster a "convergent" -- short for "conservative" and "emergent" -- movement that combines the best elements of Quaker tradition and the postmodern methods of the "emerging churches."

"I see convergent friends as people who are becoming more serious about Quakerism," Mohr said, "and not about syncretizing other religions into Quakerism."

Even so-called "hyphenated Friends," such as the Pagan-Quaker Cat Chapin-Bishop, say that "Christianity is the native language for Friends and that's the language that 350 years of wisdom is expressed in.

"I have to speak that language even if it's not the language that the spirit speaks to me."

Whatever language Quakers speak, says John Vogel-Borne, 54, a lifelong Friend from Cambridge, Mass., they must lift their voices.

"We have had a significant impact on the world," he said. "And we can still do so. We bring a particular spiritual light to the way the world is today."