Jordan and Evan Caldwell's sister sobbed as she described her twin brothers as incessant pranksters, while their father evoked their serious side as "very deep" young men who liked to discuss political, social and religious issues, before a packed funeral in Calgary.

Hundreds of mourners gathered at the massive Centre Street Church to mourn the 17-year-old twin brothers.

They died and six friends were injured while tobogganing down the sliding track at Canada Olympic Park last Saturday. The teens — who were joyriding after-hours — struck a gate separating the bobsled and luge runs.

"Today, we weep together, for all of our lives have been profoundly impacted. But out of such a tragedy, may we find hope, because of the life principles and the values that marked Evan and Jordan's lives," said Centre Street Church Pastor Miriam Mollering.

"Their lives must never be defined by how they died, but rather, by how they lived."

Among the guests at the nearly full church, which has seating for 2,300 people, was former prime minister Stephen Harper, who sat with the family at their invitation. The Caldwell boys had volunteered for Harper in the past.

Jordan and Evan Caldwell 'were bright lights to all that knew them,' their family said. (Submitted by the Caldwell family)

"What words can I say when there are no words? How do we make sense of something so senseless?" said Katie Caldwell, the twins' sister.

Pranks between those two boys was almost their own love language. But their jokes never went this far, and would never have been this cruel. - Sister Katie Caldwell

"All of you here today, despite our different beliefs and backgrounds, have something in common: a love and an ache for Evan and Jordan Caldwell. And that is something truly special."

She recalled how her brothers teased and played pranks on each other incessantly, but always with love and kindness in their hearts.

"Pranks," she said, pausing to gather her thoughts. "If only this was some cruel, cruel prank. Pranks between those two boys was almost their own love language. But their jokes never went this far, and would never have been this cruel."

'Jordan and Evan were deep'

The twins' father, Jason Caldwell, said his sons were thoughtful young men with broad interests who weren't afraid to challenge conventional wisdom and enjoyed "dissecting the challenges of our world today."

"Jordan and Evan were deep," he said. "Very deep."

Jason said the family regularly shared "special talks" about political, social and religious issues facing the city, the country and the world.

He recalled one afternoon, in particular, that Jordan came home from school, deeply troubled by a topic that had been raised in class.

"Jordan was weighed down that late afternoon and he sat with (his mother) Shauna and he shared his burden for his schoolmates, who had been discussing that day the theory — the theory — of evolution, that we, as humans, are just products of random chance," Jason said. "What a lie. What a lie that undermines our complete society."

Jason Caldwell remembered talking with his sons about politics, and social and religious issues facing the city, country and world. (CBC)

Jason said Jordan's teacher told him later that Jordan had "humbly and meekly" asked to speak in response, and rose to address his classmates.

"He simply shared and challenged those that felt there was no creator or designer, and told them that there is," Jason said.

"And that was his conviction, that there are absolutes. And there is great truth we can anchor ourselves to."

Active in school and church

Evan and Jordan were both straight-A students who volunteered and were active within their schools and their church, according to the family.

They would often not even tell each other about their successes. They were so humble. - Father Jason Caldwell

Jordan was student council president at his Westmount Charter School and active in school affairs.

Evan had recently transferred to Ernest Manning High School to further his engineering studies, a field he planned to pursue at Queen's University in Kingston, Ont.

Jason said his boys succeeded in so many ways, but were never ones to brag.

"They would often not even tell each other about their successes," he said. "They were so humble."

Leadership and volunteerism

Westmount principal Janneke Frank said Jordan had a "brilliant mind" and "led with empathy" as a senior student at the school, which includes students from Grade 5 to Grade 12.

She recalled how he was "the voice of Westmount" for two years, beginning each day's morning announcements over the school P.A. system with an enthusiastic, "Goooood morning, Westmount!" and concluding with, "This is Jordan Caldwell, signing off."

Jordan was also the founder of the Westmount Eye, a "brilliant online newspaper," an award-winning model U.N. member, an avid debater, and a mentor to other debaters, Frank said.

"He truly exemplified giftedness from the inside out," she said.

"Jordan accomplished his finest work through relationship. He held space for all of us."

The church, which has seating for 2,300 people, was nearly full. (Kate Adach/CBC)

Laura Swart knew Evan since he was a toddler and recently worked with him at refugee centre she helps run in Calgary.

She recalled how she greeted Evan on his first day of volunteering and then immediately left him on his own with a group of refugees, to see how he interacted with people who don't speak English.

"Evan moved into the crowd, extended his hand, and said, 'Heeyyy, how's it going?' He then proceeded to ask them a series of questions in the teenage vernacular," Swart said.

"The students looked at him quizzically and tilted their heads; they had no idea what he was saying. But from the moment they met Evan, they adored him. And I realized that Evan carried something in his spirit that transcended language."

Family grateful for WinSport's 'tender,' 'kind' response

Jason Caldwell said the family was grateful to paramedics, police and staff at WinSport, the facility that operates the sliding track at Canada Olympic Park, "for being so tender and kind in the way you've responded to this tragedy."

"A couple of days ago, we were invited to stand at the top of the bobsled track at WinSport," Jason said.

"Jordan and Evan's death was a metaphor. The top of the track — so smooth, so straight, so inviting — but just over the crest, the track disappears down the hill. No one knew, and none of us do, what is around the corner."