Prime Minister Jacinda Ardern, political leaders speak of mosque heroes after unprecedented day at Parliament

Speak the names of those who died and those who tried to save them, Prime Minister Jacinda Ardern said - but deprive the man who caused them of his name.

It was a powerful message as Parliament returned for the first time since those 50 Muslims were killed in attacks on two Christchurch mosques over the weekend.

Speak their names she did. She spoke of Naeem Rashid and Abdul Aziz, both of whom had tried to stop the gunman. Rashid was killed, Aziz survived.

She spoke of the police officers who had arrested the gunman, the emergency responders and the doctors and nurses in hospital. She had a promise for the families: "We cannot know your grief, but we can walk with you at every stage."

As for the man who had killed them, the only promise she had for him was that he would face his reckoning.

"He may have sought notoriety, but we in New Zealand will give him nothing. Nor even his name."

Her speech was preceded by a powerful show of religious unity in Parliament.

Speaker Trevor Mallard marched into Parliament alongside two Imams with the leaders of many other faiths marching behind.

It was also unprecedented - during sittings of Parliament the debating chamber is reserved for MPs only.

Religion and politics are normally kept apart but after those attacks that was impossible.

So there they were, the Imams, a Catholic Cardinal, a Buddhist monk, a Jewish Rabbi, an Anglican Bishop, a Presybterian Reverend, a Hindu and a Sikh walking in where the MPs waited for the special speeches on the terrorist attack in Christchurch.

Together they provided a visual display that all religions stood behind the one that was attacked last Friday. Above them sat members of the public, many Muslims who had come to watch the occasion.

For the first time, someone who was not an MP also gave the prayer. That was Imam Nizam ul haq Thanvi, who prayed in Arabic before Imam Tahir Nawaz gave the translation in English.

The prayer was one of patience. It also included thanks, for those who had helped on the day and those who had shown support after.

What the prayer did not have was condemnation or anger.

Instead, it ended with hope.

The politicians provided the condemnation and anger - as well as calls to respond with comfort and hope, and answers.

There was Ardern's stripping of the man's identity, the refusal to utter his name. Ardern also voiced anger at the social media platforms that allowed extremists to communicate and spread their beliefs, that had allowed a video of vile acts to be shown far and wide.

"They are the publisher, not just the postman. There cannot be a case of all profit, no responsibility."

National Party leader Simon Bridges queried how "hateful people" were able to congregate online and what the boundaries of acceptable discourse should be. "Because everything changed on Friday the 15th of March."

NZ First leader Winston Peters also rejected the terrorist. "Wherever terror strikes it seeks to create or provoke fear and panic. But in New Zealand it has failed. It has failed because our thoughts are not the terrorist's thoughts and his ways are not our ways. While everything else may have changed since March 15, New Zealand's essential character has not and will not."

The politicians also provided assurances that answers would follow - an inquiry into how the terrorist had come into his beliefs, why authorities had not been able to stop it, and reforms on gun laws.

Ardern's speech ended with another name, that of Hati Mohammed Daoud Nabi - the 71-year-old who was at the door of the mosque when the gunman arrived, greeting him with "hello brother, welcome."