Atlanta Mayor Andrew Young preached a sermon on nonviolence here yesterday in a tribute marking the 20th anniversary year of the civil rights march on Washington led by the late Rev. Dr. Martin Luther King, Jr.

"Nonviolence is not dead. It's very much alive in the world in which we live," said Young, a former congressman and United Nations ambassador who played a key role during the 1960s in the Southern Christian Leadership Conference, the civil rights organization headed by King.

Young spoke from the pulpit at a prayer-and-song ceremony attended by several hundred persons at the Foundry United Methodist Church, at 16th and P Streets NW. Young's 40-minute sermon was the first in a series of tributes, sponsored by the church and other organizations, to commemorate the the march led by King, who was assassinated in Memphis in 1968.

On Aug. 28, 1963, about 200,000 demonstrators assembled in Washington to demand equal rights for blacks. During the demonstration, King delivered a speech in which he said, "I have a dream that this nation will rise up and live out the true meaning of its creed, 'We hold these truths to be self-evident: that all men are created equal.'"

In his sermon, Young pointed to the now-banned Polish trade union federation Solidarity as a contemporary example of a "classical nonviolent movement." He cited several international events as evidence that nonviolence is effective. These included the Panama Canal treaties, Egyptian-Israeli peace agreement and election of a black-dominated government in Zimbabwe.

By contrast, Young said, violent tactics result in international failures, among them the Vietnam war and the current Soviet occupation of Afghanistan. "It's clear that nobody won in Vietnam," Young said.

Central to Young's sermon were three prophecies that he attributed to King. "Either there will be nonviolence or nonexistence," Young quoted King as saying. He also recalled King's statements that "injustice anywhere is a threat to justice everywhere" and that "the bombs we drop on Vietnam will explode at home in unemployment and inflation.

"I think we can avoid Martin Luther King's prophecy of nonviolence or nonexistence," Young said.