Glen H. Stassen, a Southern Baptist theologian who helped define the social-justice wing of the evangelical movement in the 1980s and played a role in advancing nuclear disarmament talks toward the end of the Cold War, died on April 25 in Pasadena, Calif. He was 78.

The cause was prostate cancer, his son William said.

Dr. Stassen championed a pragmatic approach to social justice and world peace. In a series of books beginning in 1992, he outlined a program of grass-roots activism to reduce military spending, improve the lives of the disadvantaged and give citizens a voice in international conflict resolution.

His concerns reflected positions embraced by his father, Harold E. Stassen, a former Minnesota governor and champion of the United Nations who was best known as a perennial dark-horse candidate for the Republican presidential nomination.

Dr. Stassen’s version of political activism in the 1980s and ’90s put him at odds with leaders of the religious right, who were focusing on opposing abortion and gay rights.

Dr. Stassen was among the few prominent evangelical leaders to publicly challenge the Rev. Jerry Falwell, the leader of the Moral Majority, over his electioneering on behalf of Ronald Reagan’s presidential campaigns in 1980 and 1984. And he was among the few to criticize Reagan over his domestic spending cuts, his military buildup and his use of the phrase “evil empire” in 1983 to describe the Soviet Union.

He went on to help mobilize the international disarmament movement that, by some accounts, played a role in removing intermediate range nuclear missiles from Western Europe in the late 1980s and early ’90s. At the Southern Baptist Theological Seminary in Louisville, Ky., where he became a professor of Christian ethics in 1976, Dr. Stassen clashed with administrators who urged faculty members to place ideas like prohibiting abortion, the subordination of women in the family and the literal truth of biblical texts at the core of their teaching.

After years of fighting the conservative tide there, he left in 1996 to become a professor of ethics at Fuller Theological Seminary in Pasadena, Calif., where he taught until the end of his life.

More than personal rectitude and obedience to rules of behavior, Dr. Stassen argued, Christian ethics demanded organized action to save the world from self-destruction.

“Christians need more than an ethic of ‘just say no,’ ” he wrote. “Jesus didn’t just say no to anger and revengeful resistance, but commanded transforming initiatives: ‘Go make peace with your brother or sister; go the second mile with the Roman soldier.’”

What Christians needed, he said, was “an ethic of constructive peacemaking.”

Theologians had long wrestled with the Christian response to war, and whether it was ever morally justified to kill. Two schools of thought had emerged: pacifism, which said it was never justified, and “just war” theory, which described circumstances in which killing in war was morally defensible. Dr. Stassen advocated what he called a third option: preventing wars from starting in the first place.

“Why do we only keep debating whether wars are justified?” he asked.

In “Just Peacemaking: Transforming Initiatives of Justice and Peace” (1992) and a dozen other books on nonviolence and conflict resolution, Dr. Stassen described techniques for hard-nosed negotiating in which both parties admit culpability for past deeds, take a clearheaded measure of the interests of the other side and sometimes make calculated unilateral initiatives. “Biblical realism,” as he described the mind-set for negotiations like these, “is about diagnosing sin realistically and seeking deliverance, not merely about affirming some high ideals.”

Glen Harold Stassen was born in St. Paul on Feb. 28, 1936, to Harold E. Stassen and the former Esther Glewwe. His father was elected the youngest governor in Minnesota’s history in 1938 and, after World War II, served as a United States delegate to the conference that led to the formation of the United Nations. The elder Stassen sought the Republican nomination in 1948, served as an aide to President Dwight D. Eisenhower from 1953 to 1958, and ran for president eight more times.

Dr. Stassen said his ideas were greatly influenced by his father’s religious faith and his support for the United Nations as a peacemaking force, which was at the core of his seemingly quixotic presidential bids. “My father was driven by a sense of duty — to his own country and to the world,” he told an interviewer. Glen Stassen studied nuclear physics at the University of Virginia and worked briefly in a naval laboratory after graduation before deciding that he could not contribute to the development of nuclear weapons. He quit to attend Union Theological Seminary in New York City and received his doctorate from the Duke Divinity School in Durham, N.C., in 1967.

He taught at Kentucky Southern College (now part of the University of Louisville) and Berea College in Kentucky before joining Southern Baptist Theological Seminary. In addition to his son William, he is survived by his wife, Dorothy; two other sons, Michael and David; six grandchildren; and a sister, Kathleen Berger.

In the early 1980s, while on a research sabbatical in Germany, Dr. Stassen served as a liaison between the Nuclear Weapons Freeze Campaign in the United States and several European peace groups.

He was inspired, he said, by the grass-roots activism he saw there: demonstrations drawing hundreds of thousands of people to protest plans for basing NATO missiles in West Germany and 30,000 churches joining in peace forums that filled pews to capacity.

When he returned home, he assumed a greater leadership role in the disarmament movement, serving as co-chairman of the freeze campaign’s strategy committee, a coalition of peace and labor groups that helped organize a protest in Central Park in 1982 that drew about one million demonstrators.

“A thousand things happened to bring about the slow-dawning realization that a freeze was in the interests of both sides,” Dr. Stassen wrote, referring to the 1987 treaty between the United States and the Soviet Union that finally ended the buildup. “People had more of the power and took more of the initiative than is usually perceived.”

It is always in the government’s interest to play down “the role of the people,” he added. “But the treaty would not have happened without them.”

Obituary courtesy of the New York Times: https://www.nytimes.com/2014/05/08/us/glen-stassen-theologian-who-champion-nuclear-disarmament-dies-at-78.html