Thomas Devlin was stabbed in the back five times as he returned to his home in north Belfast with two friends after a visit to a local shop to buy sweets.
The teenager's parents, Jim and Penny, were joined by dozens of Belfast Royal Academy pupils for his funeral service at the Church of the Resurrection yesterday.
Father Sean Emerson paid tribute to the talented musician, who was buried wearing an Iron Maiden T-shirt.
"The brutality of his death has made most people wonder what is going on, what is wrong in society?
"Those who murdered Thomas must have a very heavy conscience because they have committed a very evil act and that will weigh upon them for the rest of their lives."
The priest added: "However, for many of us there is a sense of despair.
"It is not just this isolated incident, it is the ongoing violence that happens almost on a daily basis. Why is it? Can anything be done? "In such times it is important that we remind ourselves that the only thing that can make any difference is for good people to continue to do good things."
The motiveless, random murder sent shockwaves through the affluent Somerton Road area where he lived, and which had largely escaped the violence of neighbouring areas.
One of Thomas's friends was also injured by a single stab wound when they were approached by two males, believed to be in their late teens or early 20s.
Two men and a juvenile were arrested following the murder but released without charge.
Thomas's schoolfriends followed the cortege from his home on the Somerton Road to the nearby Roman Catholic church on the Cavehill Road.
The mourners paused for a poignant moment at the spot where he was killed on August 10.
Fr Emerson began his homily by expressing his sympathies to Thomas' family, including his brother James and sister Megan, friends and classmates.
"The terrible pain they feel must be immense and we ask God's strength and blessing to be with them at all times."