Family and friends of Nora Quoirin gathered in Belfast to say farewell in the church where she was baptised as a baby, St Brigid's.
The body of the 15-year-old from London was cremated earlier on Tuesday morning.
Nora was found dead after a 10-day search around the Malaysian jungle resort of Dusun last month.
The teenager - who was born with the brain defect holoprosencephaly and was described by her family as "vulnerable" - disappeared on August 4.
Nora lived in London and was the daughter of French-Irish parents Sebastien and Meabh Quoirin.
The principal celebrant for the funeral service was parish priest Fr Edward O'Donnell, who was joined by Fr Pat Kelly, Nora's great uncle.
Addressing a packed church, Fr O'Donnell reflected on the girl's baptism as he told mourners of the joy Nora had brought to her family in her short life.
He described her as "gentle and innocent".
"Nora was very special, she brought so much joy to Meabh and Sebastien, to her sister, Innes, and to Maurice her brother, and to those of the wider family circle," he said.
"She, as we all know, depended greatly on others but, Nora in turn gifted others with immeasurable love and joy; before such an ability we can only feel gratitude.
"Today we return to St Brigid's united in the unspeakable pain of Nora's tragic death, united too in wordless sympathy for Nora's family.
"I ask myself, as surely you must do: 'What is the meaning of this terrible pain that has been inflicted on Nora's family?'
"We have, have we not, found ourselves wondering: if God is good and has for us the love that no human love can match, why then is there such suffering in our world?
"We do not understand, and our stumbling words are so terribly inadequate."
He added: "We who grieve for Nora hold her memory in love, believing that all the bonds of love and affection which bind us together throughout our lives do not unravel with death."
He concluded: "Meabh and Sebastien, Innes and Maurice - remember Nora's love for you, and know that she still loves you, and as you continue to love her, love one another."
When Nora disappeared from her hotel room her parents raised fears she had been abducted, insisting she would not have wandered off by herself.
However, police in Malaysia said they have so far found no evidence of abduction or kidnapping.
A post-mortem examination revealed Nora died from internal bleeding probably caused by hunger and stress.
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