"It came to me that this woman loves and worships the same God I do," says Johnson, a Christian. "I had this sharpened awareness that in that moment she was in touch with God, just as I was. It was a dawning and an awakening, and it was liberating because it liberates you from standing on a pedestal and looking down on someone else."

It also inspired Johnson to take on a life-changing mission.

At a time when many Christians, including some in his own church, were openly hostile towards a religion they believed advocated terrorism and was at war with the United States, Johnson initiated a dialog aimed at bringing Christians and Muslims together.

He has conducted a series of lectures and small-group gatherings at which more than 500 Muslims and Christians have shared their faith with each other. Not, Johnson hastens to point out, to convert anyone: "Just to understand each other."

"The dream," he says, "is that we can find a way to bridge the chasm between Christians, Muslims, Jews, Hindus and Buddhists and make Atlanta a model city. That over the next year or two, we can develop an interfaith immersion program."

Johnson is a former minister who retired in 2000 after nearly 20 years as professor of Christian spirituality at Columbia Theological Seminary in Decatur. A towering man from southern Alabama, he calls himself "a soft evangelical. I ask questions and listen rather than telling people what they ought to do or believe."

He adds, "I'm the most unlikely candidate for becoming a spokesperson about Islam."

But after several months of retirement, Johnson realized he was depressed. "Life had a dull edge," he says. "I wondered who I was now that I wasn't a teacher, preacher, traveler or speaker."

The depression was about dying. "I had started life well," he says. "Now I wanted to finish it well."

Contemplative prayer and the works of Trappist monk Thomas Merton revived him. "When you listen to God," Johnson says, "you get beneath the dogma and creeds to the essence of what religion is about. It's about God in human beings in human consciousness."

Among his insights was that the 21st century would be a religious century, and the key would be relationships between two-thirds of the world's population: 2.5 billion Christians and 1.5 billion Muslims.

"A voice in my head said, 'And you don't know anything about Islam.' Which was true. I have five degrees, four of them theological, and other religions had never been taught seriously to me."

He began reading Islamic texts and works on comparative religion, and he asked to meet a Muslim. A church friend introduced him to Dr. Jumaan, an epidemiologist at the Centers for Disease Control who is from Yemen.

While there are differences in their faiths - Muslims regard Jesus as a prophet, for example, but not divine - Johnson found that they nevertheless arrived at the same conclusions: God is compassionate, omniscient and ubiquitous.

"Everything about my faith is rooted in the stories my two grandmothers told me," Jumaan says. "No one formally taught me to pray. As a child, I had the question, 'What is God like?' My grandmother answered, 'That is like a drop in the ocean trying to understand what the ocean is like.' This is something I feel with my heart - God is present in everything. God is all around us."

In March of 2007, Johnson gave four lectures on Islam at Shallowford Presbyterian Church, expecting 30 to 40 people to attend. The room overflowed with humanity - 176 in all, and nearly one-third of them Muslims.

"My mouth was very dry," Johnson says. "There were a couple of imams (Muslim clerics), and I'm thinking they know all this stuff and I'm stumbling around in it."

Attendees met in small groups after each lecture to discuss their faiths, and the series concluded with a potluck dinner that attracted 250 people.

"We had a pastor and an imam describe how they came to the faith that gives their lives meaning," Johnson says, "And we asked people to talk at their tables about how their faith came to them."

Last September, Johnson gave three more lectures at Wieuca Baptist Church in Buckhead which led to the creation of 20 small groups with Muslim and Christian co-coordinators. They meet at least once a quarter to share faith experiences and visions for the future.

"I don't think just knowledge about [another] faith is any good," Johnson says. "You've gotta meet someone who is of the faith, who is speaking out of conviction and out of experience to really feel what Islam is like."

Plemon T. El-Amin, imam of the Masjid of Al-Islam in East Atlanta, says Johnson "puts Muslims at ease, because he's mastered the broad, historical perspective of Islam, but also some of the nuanced details."

As for a Christian speaking about Islam, El-Amin says, "People are more open to learning a new perspective from someone they respect. Ben is not trying to convert anyone, but to inform people and build understanding."

"When I heard him talk about Islam, I thought, 'We need him!'" says Jan Swanson, coordinator of the interfaith group World Pilgrims. "Many Christians are fearful of Islam, so they put up barriers. They trust Ben, so they are willing to take the first step and listen for understanding."

Johnson says Dr. Jumaan is "like a daughter" now, and he and his wife, Nan, visited her this summer in Yemen. He also participates in a contemplative prayer group that includes a Muslim, a Hindu, a Buddhist and a Jew.

"If you sit in silence, you can get deep enough into your faith that it touches another person," he says. "The reality is that at the core we're all the same."