As singers’ voices rose into the high beams of Roxbury Presbyterian Church Sunday afternoon, a tall woman in a gleaming white robe stood near the front pew, singing and swaying. Her hands stretched toward the sky.
The service officially installed the Rev. Liz Walker as pastor, but for much of the ceremony she prayed as a member of the flock. Those in attendance shoved jackets under the church’s pews to make room for an overflow crowd.
When the time came for her to speak, Walker, the first black woman to coanchor a newscast in Boston, offered only brief remarks about the power of God.
“Of all the things I’ve done, this is what I’m sure of: His grace is sufficient,” she said.
Walker has served as transitional leader of the church since 2011, and Sunday’s service made her its designated pastor.
At the service, residents joined elected and appointed officials in lauding Walker, saying that she moves effortlessly between church laity and city leaders.
She preached before President Obama, Governor Deval Patrick, and former mayor Thomas M. Menino at an interfaith service after the Marathon bombings last year.
Before Sunday’s service, Menino said Walker’s sermons “are great, but her outreach in the community” is what distinguishes her.
More than a handful of people stepped forward during the two-hour service in the hot church to offer congratulations and share stories.
Stephen Walker, a Roxbury resident who is not related to the reverend, praised the pastor for her visibility in the neighborhood.
“Sometimes I believe that Rev. Liz has a room here because she’s everywhere,” he said. “Any time the community needs her, she’s available.”
Suzan El-Rayess, development director of the Islamic Society of Boston Cultural Center, said Walker is a devoted leader in the city’s interfaith community.
“There is no other force as dynamic, as charismatic as Rev. Liz Walker when she steps up on the stage. She is a force that can probably part the Red Sea,” El-Rayess said.
The Rev. Gloria White-Hammond, co-pastor of Bethel AME Church, recalled traveling to Sudan with Walker years ago when they saw hundreds of slaves near Darfur.
“She doesn’t lead with her celebrity; she leads with her humility,” White-Hammond said.
Mayor Martin J. Walsh said he plans to turn to Walker for help in understanding and assuaging the trauma of violence in Boston’s neighborhoods.
“As a new mayor of the city of Boston, I need you to be my partner,” Walsh told the pastor in front of the congregation.
Walker took photos with her family after the official installation ceremony and downplayed the praise of city leaders, calling herself “just a new voice” and saying she is humbled to work with them in the future.
She said Roxbury Presbyterian has supported the community from its post at the corner of Warren and Woodbine streets for more than a century, and she hopes to maintain that tradition.
“This church will just continue to be the light it has been on this corner, with open doors and open hearts,” she said.Zachary T. Sampson can be reached at zachary.sampson
@globe.com. Follow him on Twitter @ZackSampson.