The recent murder of late-term abortion specialist Dr. George Tiller cast a spotlight once again on the violent fringe of the pro-life movement. What motivates them? How do they differ from the law-abiding citizens who work and demonstrate against abortion?

Some critics of the pro-life movement have recycled the old charge that what sets the handful of violent pro-lifers apart is their moral seriousness. Unlike the hypocrites who content themselves with protests and lobbying, the argument goes, those who bomb clinics and assassinate abortionists have the courage of their conviction that abortion is murder. Writes William Saletan in Slate, "If a doctor in Kansas were butchering hundreds of old or disabled people .  .  . I doubt most members of the National Right to Life Committee would stand by. .  .  . Somebody would use force." The fringe who kill expose the mainstream of pro-lifers as frauds.

The reality is much more interesting. The best studies of pro-life extremism--notably James Risen and Judy L. Thomas's Wrath of Angels--make clear that what distinguishes pro-life bombers and assassins is not the degree of their moral conviction, but their fanatical commitment to a certain understanding of political theology.

When abortion emerged as a public issue in the 1960s, most of those who fought to keep the practice illegal were Catholics. Most Protestants, including virtually all evangelicals, stayed on the sidelines. The Southern Baptist Convention even tacitly blessed Roe v. Wade, the 1973 decision by which the Supreme Court held abortion to be an individual right, overturning the laws

Roe divided the pro-lifers. Most continued to work through political channels, joining state affiliates of the National Right to Life Committee. But some concluded that either amending the Constitution or transforming the composition of the Supreme Court might not be achievable in their lifetime. In frustration, they began a campaign of sit-ins. Thus, Roe energized pro-lifers, pushing many activists into the streets.

From the beginning, their civil disobedience was shaped by their theology. The early Catholic activists came out of the antiwar left and were inspired by liberal Christians. John O'Keefe, the founder of the rescue movement (whose name derives from Proverbs 24:11: "Rescue those being led away to death; hold back those staggering toward slaughter"), was deeply influenced by Martin Luther King Jr. and especially the Catholic monk Thomas Merton. O'Keefe wrote a recruiting pamphlet, A Peaceful Presence (1978), that encouraged pro-lifers to practice nonviolent civil disobedience (blocking clinic entrances, for example, and going limp when arrested) as a spiritual act and a symbolic sharing in the helplessness of unborn children.

Early rescuers asked their friends in the antiwar movement and other liberal causes to join them but were roundly rebuffed. Yet even as those pleas fell on deaf ears, conservative evangelicals were rethinking their own political theology in ways that would forever change the rescue movement.

Given the recent history of the evangelical right, it is easy to forget just how apolitical large numbers of conservative Protestants were during most of the 20th century. Evangelicals, in particular, tended to believe that saving souls by spreading the gospel should take priority over political engagement. Most also accepted a view of the end times known as premillennialism, which teaches that the world must fall even deeper into sin before Christ returns to establish his thousand-year reign. This eschatological view encouraged separation from the world and made social reform seem futile at best.