Prince William was speaking after arrived at Al Noor mosque with survivors of the Christchurch terror attack.
He said he couldn't believe the news of the mosque attacks on March the 15th.
He said he had reasons to reflect on grief and sudden pain and loss in his own life.
He says an act of violence was designed to change New Zealand - " but instead the grief of a nation revealed just how deep your wells of empathy, compassion, warmth and love truly run".
"You showed the way we must respond to hate - with love," the Prince said.
"The forces of love will always prevail over the forces of hate."
He said people should not forget the sadness, shock and pain but said grief could help you live up to the values you espouse.
New Zealand looked like it would fall victim to those intent on promoting fear and distrust - but he says Kiwis and the people of Al Noor and Linwood mosques had other plans.
"In a moment of acute pain, you stood up and you stood together. And, in reaction to tragedy, you achieved something remarkable."
William told the audience: "To the people of New Zealand and the people of Christchurch, to our Muslim community and all those who have rallied by your side, I stand with you in gratitude to what you have taught the world in these past weeks."
He added: "Extremism in all forms must be defeated."
As he stepped out from his chauffeured BMW outside the mosque a man shouted out "Kia Ora!"
The Duke of Cambridge arrived at the mosque proceeded by a large contingent of police and watched overhead by the police eagle helicopter.
The Prime Minister Jacinda Adern, Imam of Masjid Al Noor Gamel Fouda, Minister for Greater Christchurch Regeneration Megan Woods and Mayor of Christchurch Lianne Dalziel greeted him just inside the gates.
About two dozen members of the public and a large number of media watched his arrival from over the road.
Prince William is in the country to pay respects after last months mosque attacks.
He met with emergency service personnel at the justice precinct yesterday afternoon and with paramedics at Christchurch hospital this morning.
Prince William earlier Christchurch Hospital to visit victims of the mosque attacks.
About 100 people cheered and clapped as the Duke of Cambridge, stepped out of his vehicle, some grouped in the windows of surrounding buildings after 9am this morning.
Among the group were hospital staff, workers from businesses and construction sites and curious passers by.
The duke arrived in a motorcade of over half a dozen vehicles, including a paramedic, armed defenders squad.
Security detail is tight, with a helicopter flying overhead and a team of police officers and security staff roaming the streets surrounding the hospital's entrance.
NZME reported that while the Prince has a private meeting with the shooting survivors at Christchurch Hospital, local Muslims are filing in to Al Noor Masjid, where William will appear later this morning.
Prime Minister Jacinda Ardern has arrived at Al Noor Masjid wearing a headscarf.
She was met by Christchurch Mayor Lianne Dalziel and Minister for Greater Christchurch Regeneration Megan Woods.
A large crowd is gathering across the road in Hagley Park to watch the dignitaries arrive, awaiting Prince William who is expected soon.
What you need to know:
- Prince William will visit Christchurch Hospital and Al Noor Mosque today. He will also visit Linwood Mosque and lay a wreath at the Earthquake National Memorial. The public will have a chance to meet Prince William after the wreath laying when he takes a short walkabout across the North Bank reflection area.
- Yesterday Prince William attended the 11am Anzac Day service at the Auckland War Memorial. He later flew to Christchurch where he visited the Justice and Emergency Services Precinct and met Commissioner of New Zealand Police Mike Bush and Superintendent District Commander Canterbury John Price.
- His visit is focused on the royal family's support in the aftermath of the 15 March mosque shootings.
With NZME
