The shot that echoed in the Memphis dusk 50 years ago still reverberates through our national life, yet there is so much about the Rev. Martin Luther King Jr. we find hard to absorb.

In our long effort to moderate King, to make him safe, we have forgotten how unpopular he had become by 1968. In his last years, King was harassed, dismissed and often saddened. These years after Selma are often dealt with in a narrative rush toward martyrdom, highlighting his weariness. But what is missed is his resilience under despair. It was when his plans faltered under duress that something essential emerged. The final period of King’s life may be exactly what we need to recall, bringing lessons from that time of turmoil to our time of disillusion.

Celebrating the march out of Selma, Ala., and his early prophetic optimism made sense in the heady Obama years. Now, we need King’s determined faithfulness.

Once refusing to get on a flight in 1967, King called his wife, Coretta, from the airport saying, “I get tired of going and not having any answers.” His opposition to the Vietnam War cost him support. At a time of emerging Black Power, King’s dream of integration and nonviolence seemed to many insufficient, almost passé. Yet he died still trying to confront “the evil triplets,” how “racism, economic exploitation and militarism are all tied together.”

A week before his assassination, King told performer and activist Harry Belafonte that he worried the civil rights movement was “integrating into a burning house.” But when Belafonte asked what they should do, King replied, “I guess we’re just going to have to become firemen.” As he fought to be heard, to still be relevant, King’s determination awed those close to him, even as they feared for his emotional and physical welfare.

An unguarded King who still speaks to us can be found in transcripts of Southern Christian Leadership Conference retreats. He felt most comfortable sharing his own emerging radicalism with his fractious disciples in private - for example at the Penn Center on St. Helena Island, South Carolina.

There, he told his staff in 1966, “I am still searching myself. I don’t have all the answers.” When they gathered a year later, five months before his assassination, it was clear to King that “the movement for social change has entered a time of temptation to despair.” He felt that temptation, too. Sensing they were running out of time, he said that mass civil disobedience was needed to spur more action in cities, in order to take on segregation and economic injustice beyond the South. He would remind them, “The great burden of this will be on you … . I can’t do it by myself.”

King offered his staff - and us, a nation still reluctant toward his last vision - a challenge. He knew the temptation to walk away, to save himself, but he concluded, “I’m not talking about some kind of superficial optimism which is little more than magic. I’m talking about that kind of hope that has an ‘in spite of’ quality.” To a reporter two days after the gathering, King declared, “We have got to confront the power structure massively.”

In an Atlanta retreat in January 1968, King said, “We live in a sick, neurotic nation … . And I don’t want to analyze anybody but myself.” Even as he moved through that time of lack of belief in himself, his staff loved and revered him. Yet they resisted now, often telling him his radical take on economic injustice was not only wrong but also bad strategy.

His anguished conclusion at his last retreat in Atlanta was simple yet excruciating: “Hope is the final refusal to give up.” King did not just assert this but also lived the belief, by continuing to put his body into his nation’s gun sights. His lack of answers did not keep him from his destiny - which was not fate so much as the result of his choice to show up, to keep on.

King realized his movement’s goals could no longer be as clear as desegregating lunch counters or gaining the right to register to vote. As early as 1966, King said at Howard University that the totality of society’s economic ways must be in their sights, and “not only will it mean the restructuring of the architecture of American society but it will cost the nation something … . If you want to call it the human rights struggle, that’s all right with me.” When it came time to put together a Poor People’s March, it would cost King everything.

Fifty years later, it would look too familiar to the King of 1968 to see our continued economic inequality, hawkishness, backlash to civil rights gains, and racist violence from Charleston to Charlottesville. His response then was to resist exhaustion from the deluge of issues and to enlarge his work instead, hold firm his insistence.

Every era finds the King it needs. The version we need now is a King who pressed on through doubt to see a radical vision, as we must find one to match the challenges we face. King ran out of certainty but never faith.