Daniel Oquendo, the father of Avonte, touched his son’s coffin at St. Joseph’s Church in Greenwich Village on Saturday. Chang W. Lee/The New York Times

Avonte Oquendo’s smiling school portrait was on display next to the white coffin, decorated with four carved angels, that held his remains during his funeral on Saturday. It was also on the mourners’ lapels and the screens of cellphones clutched by the scores of New Yorkers who came to pay their respects but who had never met him.

They said they considered Avonte, who disappeared from his school in Queens in October and whose remains were found along the East River earlier this month, a child of the city itself.

At the boy’s funeral, as each additional stranger joined a line that snaked down the block from St. Joseph’s Church in Greenwich Village, the public grief sometimes grated against the private grief of Avonte’s mother, father, brothers and family.

“Nobody feels this loss except the parent — it’s your kid,” David H. Perecman, the lawyer for Avonte’s family, said as he stood outside Greenwich Village Funeral Home on Bleecker Street, where a separate service was held before the funeral.

The outpouring of support, he said, was “a two-edge sword,” adding, “I’m sure to some extent it’s a little annoying because it’s unwanted attention, but to some extent you know that there are people there for you.”

“I hope it gives them solace,” he said.

Avonte, who was 14 when he disappeared, had severe autism and was nonverbal.

Inside the funeral home, which was open only to family and friends, attendees said it was silent, all eyes resting on the gleaming white coffin. The services by the funeral home were donated by its owner, Peter DeLuca. The church service was open to the public. Cardinal Edward M. Egan, the former archbishop of New York, delivered the Mass.

Some of those lined up outside said they had come because they were moved by the plight of the lost child, by the city’s extensive search efforts — which covered over 400 subway stations and employed bloodhounds, scuba divers and helicopters — and by his family who never gave up.

Others like Margaret Coaxum, 50, were drawn to the church by a sense of commonality: Ms. Coaxum walked to the Mass holding the hand of her 15-year-old son Elijah Thompson, who has autism. Elijah pressed a plastic model train to his cheek.

“Avonte and Elijah both had a fascination with trains,” she said, something she had read in news reports. “Ever since it happened, my mind was on this family.”

In Cardinal Egan’s eulogy to the packed church, he spoke of how Avonte had handled his disability with “nobility” and “grace” and praised him as a child of such spirit that he inspired the “entire tristate community.”

And yet amid the sense of unity inside the church, there were points of friction between those who had adopted Avonte as a cause, and those who knew him as a real child. “Keep the outsiders back!” one woman said as she tried to make her way through the crowd into the service.

Even some people like Tamara Branch, who said she had volunteered daily with the search, seemed to be caught up in the fervor that had surrounded the disappearance. Her son Dante Acker, 7, held her as she sobbed through the service; she was later asked to leave by another attendee after she took a picture inside the church.

“I couldn’t sleep at night because I was thinking about Avonte,” she said earlier, in tears, “and when I’d wake up, he was the first thing on my mind.”

Toward the end of the service, Mr. Perecman, who is suing the city on behalf of the family, accusing the school, in Long Island City, of letting Avonte step out unchecked, took the pulpit. Standing beside a towering display of white carnations and white roses, he called for what befell the boy to prompt reform in city schools.

The quiet audience applauded, and many repeated his refrain. The words ricocheted around the church. “Never again.”