It was the kind of Pope John Paul II quotation that was powerful and prophetic -- but hard to print on a political bumper sticker.

"America will remain a beacon of freedom for the world as long as it stands by those moral truths which are the very heart of its historical experience," he said, during his 1999 U.S. tour. "And so, America: If you want peace, work for justice. If you want justice, defend life. If you want life, embrace truth -- the truth revealed by God."

One American activist who paid close attention was Ronald J. Sider, a Mennonite theologian who was already several decades into a career built on asking Americans to ponder precisely that equation.

Politicians on left and right would cheer as John Paul attacked the modern world's "culture of death," said Sider. But, in private, Democrats and Republicans would groan.

"People on the left will love what he had to say about the death penalty and racism and caring for the poor," said Sider, when I reached him by telephone. "But many liberals are going to squirm because he ties these issues directly to traditional Christian teachings on abortion and euthanasia and family life. Meanwhile, some people on the right will squirm because the pope made it very clear that he links these pro-life issues to the death penalty and poverty, sickness, hunger and even the environment."

Sider added: "We live in an age of incredible relativism in this society and even in the church. We live in a land that seems to have lost its way."

These kinds of tensions defined Sider's own struggles as a hard-to-label political activist and ecumenical leader. He died on July 27 at the age of 82.

Christianity Today listed Sider's classic "Rich Christians in an Age of Hunger" as one of the 20th century's most influential religion books. The flagship evangelical magazine also ran this headline with a cover story about Sider's career -- "Unsettling Crusade: Why does this man irritate so many people?"