"Many of us are looking for reasons: Why this senseless violence?" said Father Michael Speziale at Christ the King Roman Catholic Church, the home parish for the Davies family.
Speziale urged the congregation to pray for Davies "one surgery, one rehab, one moment at a time."
He also urged attendees to pray for the perpetrators of violence, especially against police officers.
"If we want true healing and true peace, we need to pray for the other side as well," the priest said.
Eric Torres, 31, is being held without bail on charges including attempted murder, assault on a law enforcement officer, and aggravated assault. Police said he was driving a car packed with heroin when he was stopped and fled to a mini-mart, where he shot Davies during a confrontation with officers.
The healing Mass was organized by the Fraternal Order of Police Lodge 5 and the union's auxiliary.
At the celebration of Moses Walker's life, police blocked off North 10th Street, where children played ball. Adults traded stories of Walker while listening to live music and a comedy act and watching dance performances.
"He was a man I could look up to, a reason to grow up right," said Anthony Walker Jr., 21, the fallen officer's oldest nephew.
Walker, 40, a 19-year veteran, was on his way home from his shift at North Philadelphia's 22d District when two men approached him on Cecil B. Moore Avenue and fatally shot him during a robbery.
Sunday's anniversary of Walker's death will be painful, said Wayne Lipscomb, 59, the officer's mother.
"It's going to be a very, very sad day," she said.
The Saturday celebration was a way to thank a community that had supported the family, she said.
"Knowing Moses, he would want us to rejoice, be thankful for his life," she said.
Speaking to the crowd gathered inside the recreation center at the end of the celebration, Lipscomb said she hoped the neighborhood would learn from the violence it has seen.
"I just have one request to ask of y'all: When you get into an argument with somebody, please just walk away," she said. "We have lost too many good soldiers in this area."
Contact Andrew Maykuth at 215-854-2947, @Maykuth, or firstname.lastname@example.org.