NEWTOWN, Conn. -- A former leader of one of the country's most prominent liberal Protestant churches told residents on Sunday, weeks after one of the deadliest school shootings in U.S. history, that the Rev. Martin Luther King Jr.'s words "are needed now more than ever before."

The Rev. James A. Forbes Jr., the first black minister to lead New York's historic Riverside Church, spoke Sunday night at the Newtown Congregational Church in a service honoring King and the school shooting victims.

About 300 residents filled the church for the community worship service, called "For the Healing of Newtown." Forbes delivered a sermon calling for a transformation and healing of communities.

"The saddest face I ever saw on Martin Luther King was at the funeral of the four little girls slain in Birmingham, Alabama," he said. "We ask today, as King did then, `Lord, what can come out of this that will honor those lost in this tragedy?'"

Twenty Sandy Hook Elementary School first-graders and six school officials died in the Newtown shooting last month. The gunman who killed them had killed his mother at home before going to the school and later committed suicide.

Forbes' message of transformation was delivered to the Newtown community a day before the federal holiday honoring King's legacy and a little more than a month after the Dec. 14 school shooting.

The senior minister of the Newtown Congregational Church, the Rev. Matt Crebbin, welcomed the congregation and spoke of the long journey ahead.

"Though we are all interconnected, our destiny lies in our ability to be one, as a community and as a nation," he said. "Tonight we gather to heal and mend hearts."

As the congregation sang the hymn "When Aimless Violence Takes Those We Love," many fought back tears and others simply wept.

Forbes told the congregation his message would be one of hope and healing.

With great passion, he spoke of his experiences during the civil rights movement and the struggles and challenges along the way. But, he said, one way to get encouragement is to recognize when progress is made.

"As a community, overcoming a tragedy will take time, but progress will be made," he said.

Forbes said that King believed in the power of community and faith and the need for good to come from tragedy. He stepped down from the pulpit to be closer to the congregation as he raised his voice to finalize his message.

"We have seen that violence can strike anywhere," Forbes bellowed. "Yes, King talked about violence, but he also talked about transformation and healing in the wake of violence."

He then asked people in the church to consider something: "What if history records what happened in Newtown and that leads to a new America?"

"Maybe if we listen to the Spirit, we as a town will be able to stay out of the depths of despair," he said. "If we listen to the Spirit, there will emerge a beacon of light that can lead an entire nation."

Crebbin said this was a fitting time for Forbes, who was leader of the Riverside Church on Sept. 11, 2001, but retired in 2007, to visit Newtown, which is about 60 miles northeast of New York City.

"He's been able to share his insight about grief through his experience with 9/11," Crebbin said. "In the midst of the grieving, we can't try to fix the grief. We need to help with the grieving. It won't be the same life."

Everyone stood to sing "We Shall Overcome" as the service ended. Forbes, founder of the Healing of the Nations Foundation, walked down into the congregation to take the hands of those sitting across the aisle from each other and connected the crowd into one.