Liz Walker may be best remembered locally for her two-decade career at WBZ-TV, where she was the first African American to anchor a newscast in Boston, but she drew on her current role to inspire the 330 graduates at the School of Public Health Convocation. The pastor of Roxbury Presbyterian Church, she urged them to “practice grace.”

“There are voices out there that seem to insist the world is divided between us and them,” she told the audience at BU’s Track & Tennis Center on May 20. “I have been to many places in the world, and I am here to tell you: There is only us.”

Walker was an Emmy-winning journalist and one of Boston’s most well-known faces when a trip to South Sudan in 2001 changed her career course. Outraged by the human rights atrocities she saw there, she cofounded the nonprofit My Sister’s Keeper, which provides economic and educational opportunities for Sudanese women and girls, and helped establish the Sisterhood for Peace Initiative, a network of Sudanese women of various races, religions, and ethnicities working together to promote peace and justice.

That experience led Walker to Harvard Divinity School, where she earned a Master of Divinity in 2005. Under her leadership, Roxbury Presbyterian Church is home to the Cory Johnson Program for Post-Traumatic Healing, which addresses the neighborhood’s high rate of post-traumatic stress disorder (PTSD) and works to improve mental health services for those with PTSD and help them develop the skills needed to manage it.

She focused her address on “an idea that I think will ultimately save the world,” she said: the concept of grace. “Grace is thought of in the church as divine forgiveness, but I would argue that grace is much more than that.” The Jamaica Plain resident used the Jamaica Way as a simple example: during rush hour “nobody’s going fast, but everybody’s mad on the Jamaica Way,” she said. “The traffic is bumper to bumper, but no one lets you in.

“So here’s my definition of grace: Just let somebody in.”

Walker said she came to the idea of grace in 2001, when she first traveled to South Sudan for a news story investigating allegations of slavery in the midst of the Second Sudanese Civil War.

“This is a part of the world that seems always caught in conflict,” she said. “There are always wars, there are always droughts and famines, both natural and man-made. People are killed by the thousands and by the hundreds of thousands, and in the midst of chaos I was exposed to the kind of grace that I’ve never seen before.”

She attributed that sense of grace to the same ethnic, religious, and tribal affiliations usually blamed for conflict. “In South Sudan people say, ‘We belong to each other,’” she said. “On a certain level there are wars and conflicts, but underneath there are people who belong to each other.”

“There are voices out there that seem to insist the world is divided between us and them…I am here to tell you: There is only us,” Walker told the SPH grads.

Walker spoke about her work at her Roxbury church, collaborating with Boston Medical Center and other institutions to address PTSD healing. “We have decided to focus on the long-term effect of violence, loss, and grief, what happens after the yellow police tape is down and the physical wounds have healed,” she said, noting that such trauma is not limited to war or urban violence, but in an interconnected world, is experienced by everyone.

“All you have to do is turn on your television for a while and watch the news. Once you watch for a few minutes you start twitching, and then you feel like you want to slap somebody. That’s trauma, and it’s slowly eating away at our ability to practice or even see grace in the world.”

Because grace becomes more and more difficult every day, she said, it becomes more and more necessary. “We don’t have to agree. We don’t have to hang out together. We don’t have to hide our anger, but in seeing each other’s humanity and in seeing something possible in the other person, we can elevate the discourse, and in the process, elevate each other.”

In closing, Walker urged the SPH graduates to recognize those connections, to see the possibilities in others and “give them a break,” wherever they might find themselves in their work in the field of public health. “In that moment, you will have lifted all of us,” she said.

Student speaker Cassandra Osei (SPH’17), who is committed to tackling structural inequities, stressed the importance of recognizing individual stories within vulnerable populations. A spoken-word poet, Osei’s speech was given as a spoken word performance. She told her own story as an example of how determinants of health intersect in individuals. The daughter of Ghanaian immigrants, she “was raised in Chicago,” she said, “and I lived the results of structural injustice.” She told of how immigration, racism, sexism, and trauma have affected her life.

“Misogynoir is real,” she said, referring to misogyny directed towards black women. She described it as “where racism and sexism meet.”

Osei urged fellow graduates to remember that “there’s always a determinant you may not know embedded in another person’s story.” Effective public health work requires being humble enough to recognize that.

Her work at SPH has focused on the mental health of black women. “Mental and public health have a long way to go before they can understand the systemic complexities of a black woman’s story,” Osei told the audience. She is currently designing an online intervention aimed at decreasing the incidence of mood disorders among young black women in Chicago.

Two SPH faculty members were honored for teaching and scholarship at the ceremony. Howard Cabral, a professor of biostatistics and codirector of the Biostatistics Graduate Program, received the annual Norman A. Scotch Award for Excellence in Teaching, for outstanding and sustained contribution to the education program. Judith Bernstein, a professor of community health sciences, was given the Faculty Career Award in Research and Scholarship.

Sandro Galea, dean of SPH and Robert A. Knox Professor, congratulated Sophie Godley (SPH’17), a clinical assistant professor of community health sciences, on being chosen to receive a 2017 Metcalf Award for Excellence in Teaching, one of the University’s highest teaching accolades, which was presented to her at the main Commencement ceremony the next day. Godley graduated with a doctorate at the SPH convocation, to cheers from former students.

Ayobami Olanrewaju (SPH’17) was awarded this year’s Leonard H. Glantz Award for Academic Excellence, and Karen Smith, community health sciences department financial manager, received the Dzidra J. Knecht Staff Award for Distinguished Service.

Michelle Samuels can be reached at msamu@bu.edu.