After days of angry headlines about the murder of an abortionist, one of America's most articulate defenders of life knew it was time for candor. "If anyone has an urge to kill someone at an abortion clinic, they should shoot me," said the late Cardinal John O'Connor, preaching to his New York City flock in 1994. "It's madness. It discredits the right-to-life movement. Murder is murder. It's madness. You cannot prevent killing by killing."

The cardinal's famous soundbite was part of a larger debate during the mid-1990s, as pro-life leaders articulated precise reasons why frustrated activists on the fringe of their movement should reject violence. This debate remains tragically relevant, after the killing of late-term abortionist George Tiller while he was serving as an usher at Reformation Evangelical Lutheran Church in Wichita, Kan.

The alleged gunman Scott Roeder has expressed sympathies for the views of activists who -- as in this "Defensive Action Statement" at ArmyofGod.com -- argue that this kind of violence is morally justified.

"We ... declare the justice of taking all godly action necessary, including the use of force, to defend innocent human life (born and unborn). We proclaim that whatever force is legitimate to defend the life of a born child is legitimate to defend the life of an unborn child."

This is precisely the argument that O'Connor and others fervently opposed 15 years ago. Quoting the Catholic Catechism, Pope John Paul II, Gandhi and other sources, he attacked the ancient consequentialist argument that good ends justify any means.

"Where does this spiral end? How is it limited? Surely, we are all as tired of abortion as we are tired of murder. But we must fight murder without conforming to it or condoning it," wrote the cardinal, as part of "Killing Abortionists: A Symposium" in the journal First Things.

"Let us attend to God's revelation: 'Do not be conquered by evil, but conquer evil with good' (Romans 12: 21). ... No Christian, however well-intentioned, has the moral right to declare himself the sole detective, district attorney, judge, jury and supreme court in our democratic society and on his own authority set aside the natural law and the Ten Commandments, allegedly to advance the fifth of those Ten Commandments."

While frustrated by new political defeats, mainstream abortion opponents have continued to embrace this viewpoint. The list of organizations strongly condemning Tiller's death includes the National Right to Life Committee, U.S. Conference of Catholic Bishops, Americans United for Life, Focus on the Family, Concerned Women for America, Care Net, the Susan B. Anthony List, Priests for Life and many others.

"Murdering someone is a grotesque and bizarre way to emphasize one's commitment to the sanctity of human life," noted Richard Land, president of the Southern Baptist Ethics & Religious Liberty Commission. "People who truly believe in the sanctity of human life believe in the sanctity of the lives of abortion providers as well as the unborn babies who are aborted."

Land noted that another important document emerged from the 1994 debates, produced by a circle of Southern Baptist theologians. A major theme in this "Nashville Declaration of Conscience" is that Americans continue to have many legitimate ways to challenge their government's abortion laws, short of violent revolution.

Ultimately, this document concluded, it is the "people of the United States, acting through legitimate governmental institutions, who are responsible and ultimately accountable for immoral laws permitting and protecting the taking of unborn human lives. ... Legalized abortion on demand is the single gravest failure of American democracy in our generation. But we recognize it as a failure of a legitimate democracy rather than as the imposition or decree of an illegitimate regime."

Abortion continues to stretch the "American body politic near the breaking point" because the issue pivots on fundamental moral questions, noted ethicist David Gushee of Mercer University, who drafted the Nashville document early in his academic career. In terms of history, only debates over slavery cut this deep.

But it's wrong to blame abortionists, politicians, talk-radio hosts or any other single group of people for this conflict, he said. All Americans need to look in a mirror.

"In a vast, diverse, squabbling, pluralistic democracy, even on matters of the gravest and most heartfelt significance we face sometimes irreconcilable differences," said Gushee. "If that democracy is to survive, we must learn to deal with them without killing each other."