"I deeply believe that if we as evangelicals remain silent and do not speak up in defense of the poor, we lose our credibility and our right to witness about God's love for the world," Dr. Warren, author of "The Purpose-Driven Life,"wrote in an open letter to President Bush, whom he described as his "co-worker in Christ."
Religious liberals and conservatives have occasionally worked together over the past decade or so, for example, successfully pressing for U.S. involvement in ending the Sudanese civil war, said Rabbi David Saperstein, director of the Religious Action Center of Reform Judaism.
He said he thought that on the subject of world poverty, the alliance would be deeper and longer-lasting.
"It goes to such a core religious issue," he said. "All Abrahamic faiths and most religions have as a core value caring for the poor.
"I suspect that we're seeing something that will have a lasting impact."
Add the star power of Live 8, and poverty is suddenly getting the sort of attention it hasn't received in years.
"It's unfortunate that it takes celebrity involvement for people to care. But if it brings attention to these issues, it benefits us and benefits the people in need," said Arif Shaikh, a spokesman for Islamic Relief. The international charity was founded in England in response to the African famine of the mid-1980s-the same famine that led to the original Live Aid.
Beyond star appeal, activists cite several reasons for the renewed emphasis on poverty among people of faith and the American public at large.
The Sept. 11 attacks led many people to focus on the United States' relationship to the rest of the world. The outpouring of support and concern after the Asian tsunami again led people to think about global poverty. And coverage of the ethnic slaughter in the Darfur region of Sudan has drawn sympathetic attention to Africa's problems.
The issue has also been propelled by President Bush's pronouncements early in his presidency committing to fight AIDS and poverty in Africa-and what many see as the administration's failure to make good on those commitments, said John McCullough, executive director of Church World Service, a Christian relief group affiliated with the liberal National Council of Churches.
"The United States has historically underserved its neighbors on that continent," Mr. McCullough said. "The capacity of the United States to use its resources to address hunger and poverty throughout the world is enormous."
As just one example of the possibilities, said Arif Shaikh of Islamic Relief, if all currently-unused land in Sudan alone were cultivated, it could feed all of Africa.
"The biggest challenge is letting people know a lot of these problems are fixable," he said. "There's no reason for people to be starving."
What's most needed, many say, is the political will.
Politicians often say poverty doesn't resonate with the public as an important issue, Mr. Wallis said. He disagrees.
He cites a November 2004 Zogby poll in which Americans were asked to identify the most urgent moral crisis facing the country. More cited "greed and materialism" and "poverty and economic justice" than abortion or gay marriage.
"We have to demonstrate that there's a movement afoot," he said. Politicians, he added, will "pay attention when they see that movement."