A priest at the funeral of one of the Disappeared, Kevin McKee, has said after "43 years of pain" it was important that he received a Christian burial.
The remains of Mr McKee, 17, and Seamus Wright, 25, were found in a single grave in June.
The Disappeared are victims murdered and secretly buried by republicans during the conflict.
Fr Michael Murtagh told mourners: "We acknowledge the 43 years of pain."
"At times there were very few to turn to and it was a lonely road for them to travel," he said.
A requiem mass for Mr McKee was held at St Peter's Cathedral on the Falls Road in Belfast on Monday.
Over the past 16 years, the Independent Commission for the Location of Victims' Remains (ICLVR) has searched for 16 people who were officially listed as the Disappeared.
The remains of 12 of the victims have been recovered and formally identified to date.
The bodies of Mr McKee and Seamus Wright were found unexpectedly during a search for another of the Disappeared, Joe Lynskey.
Mr McKee was buried beside his mother in Blaris cemetery in Lisburn.
The funeral of Mr Wright will take place in west Belfast on Tuesday.
Father Michael Murtagh thanked the work of the Commission and urged those with information to take a "leap of faith" and come forward.
"We encourage those who might have further information to recover the remaining four bodies to take that leap of faith and share what they have with the relevant confidential channels.
"The relief and closure it gives to family and loved ones can never be under estimated," he said.