Lyra McKee's legacy should be a society where labels become "meaningless", her sister has said.
The reporter, 29, who was shot dead by dissident republicans on Thursday in Derry, was gay and non-sectarian.
She broke down barriers in a divided community in Northern Ireland, mourners at her funeral were told.
Politicians separated over identity issues were urged to get back to work in her name.
She relished difference and embodied an alternative vision of a Northern Ireland at peace, a friend told the thanksgiving service in Belfast.
Taoiseach Leo Varadkar, President Michael D Higgins, Tánaiste Simon Coveney, UK Prime Minister Theresa May and Labour leader Jeremy Corbyn were among those who attended.
The service of thanksgiving was held in the Church of Ireland's St Anne's Cathedral, a short distance from her north Belfast home.
Ms McKee was killed by indiscriminate fire as she observed clashes between police and New IRA dissidents on the Creggan estate in Derry on April 18.
Her sister Nichola Corner said she was the kindest and most gentle person the world will never forget.
"We can create a society where labels are meaningless."
She added every single person should get the chance to grow up and make their dreams come true.
"This is Lyra's legacy and we must carry it forward.
"This is the gift that God gave the world on the 31 of March 1990.
"We are all responsible for helping God's will to be fulfilled, each and every one of us."
She paid tribute to her sister's bond with her mother.
"Whilst a broken heart can never be mended and an empty space can never be filled, the unconditional love that they both shared for each other will continue for eternity."
Her friend Stephen Lusty said she embodied a future of finding commonality, enjoying difference in others.
They had been robbed of a talent destined to become a stateswoman, with only holes left behind, he said.
He said Ms McKee's lasting legacy should be peace.
"We have two choices, we can look into the holes and wait forever... or we can fill those holes today.
"Today we grieve but tomorrow let us fill that hole by adopting Lyra's future and vision."
Mr Lusty said his friend was planning to propose to her partner Sara Canning.
She showed him pictures of the engagement ring.
“She made me put a date in my diary for the wedding in Donegal in 2022 and gave me strict instructions to wear my kilt, which she always wanted to borrow, adorn it with some Harry Potter, and to find or re-find my own version of Sara.”
In introductory comments, Dean Stephen Forde said: "Lyra was a person who broke down barriers and reached across boundaries.
"This was her hallmark in life, this is her legacy in death."
Today should mark a new beginning for Northern Ireland, a priest told mourners.
Fr Martin Magill asked: "Why does it take the death of a 29-year-old woman with her whole life in front of her to get to this point?"
Dissident republican gunmen who killed the Belfast-born journalist should lay down their arms, Fr Magill added.
He urged politicians at Northern Ireland's suspended powersharing administration to work together to produce a better life for young people.
Catholic priest Fr Magill said: "I dare to hope that Lyra's murder on Holy Thursday night can be the doorway to a new beginning. I detect a deep desire for this."
Fr Magill said: "To those who had any part in her murder, I encourage you to reflect on Lyra McKee, journalist and writer, as a powerful example of 'The pen is mightier than the sword'.
"I plead with you to take the road of non-violence to achieve your political ends."
Since the killing many have condemned the culture of violence and coercive control practised by dissidents, the clergyman said.
"We need to send a very different message and so I appeal to those who have information about Lyra's murder but who haven't yet come forward to do so now.
"If you want to see an end to these brutal rules, and see a new society built on justice and fairness, on hope and not fear, then you can help build that society by letting the police know what you know."
He called on political leaders to break the Stormont negotiations impasse.
"I pray that Lyra's murder may be the catalyst needed for parties to start talking, to reform that which was corrosive in previous assemblies and to begin anew."
Those attending the funeral were asked to wear Harry Potter and Marvel Comics merchandise in tribute to the journalist's passion for both.
The congregation was led by Ms McKee's partner Sara Canning, 35, her mother Joan McKee, 68, brothers Gary and David and sisters Joan, Nichola and Mary.
Her family have paid tribute to a "gentle, innocent soul" whose "desire to bring people together made her totally apolitical".
The New IRA is an amalgam of armed groups opposed to the peace process and it recently claimed responsibility for parcel bombs sent to London and Glasgow in March.
Police believe the violence in Derry was orchestrated in response to an earlier search by officers aimed at averting imminent trouble associated with the anniversary of the Easter Rising.