While Christians who move in the circles around Sant'Egidio may debate the right approach to other religions, Evangelicals who call themselves "Great Commission Christians" have no such hesitations. For them, explicit conversion to Jesus Christ is the name of the game.
The most determined movement in "Great Commission Christianity" today focuses upon what they call the "10/40 window," meaning a swath of the globe between 10 degrees latitude north of the equator and 40 degrees south of the equator. It includes Northern Africa and the Middle East, India and China, representing the part of the world with the lowest percentage of Christians. Of the 56 countries in the 10/40 window, 44 are majority Muslim states.
Such "10/40" evangelists are a reminder that gatherings such as the one in Assisi this week, while fascinating in their own right, are not representative of the full range of Christian opinion.
"The claims of Jesus Christ are so exclusive that it's a narrow door," said Warren Larson, director of the Samuel Zwemer Center for Muslim Studies at Columbia International University in Columbia, South Carolina. "Salvation is through Christ and his work on the Cross, not by remaining a Muslim."
I spoke in late August with Larson, who spent 23 years as a missionary along with his wife in a small Pakistani town.
Surveying the contemporary scene, where some analysts see the potential of a "clash of civilizations" in rising Islamic fundamentalism, Larson sees missionary opportunity.
"It's creating a fertile climate for conversion," he said.
Larson cited a 1995 study of 32 Muslim converts to Christianity, or "Muslim Background Believers," carried out by an international missionary body. Larson said it found that "the harshness of fundamentalism, the cruelty of the regime in Iran, and other things happening in the Muslim world" were important factors in their decision.
Though he would not offer numbers, Larson said that 10/40 missionary efforts are paying off among Muslims in places such as Iran, Western Africa, and Central Asia. He argued that disillusionment with the Islamic revolution in Iran has created a "growing movement" of Christian converts in that country. He pointed to the fact that there are now 60 Iranian evangelical churches in the United States, serving Iranians who have immigrated.
"Muslims never convert suddenly, easily, or without great deliberation given the cost," he said, referring to social ostracism and even death threats.
Larson enthusiastically endorsed the 10/40 campaign.
"In the end-time," he said, "God will bring more and more of these people to himself in these black parts of the world."
That, to be sure, is a vocabulary one did not hear in Assisi.
The e-mail address for John L. Allen Jr. is firstname.lastname@example.org