"It is difficult to look past the wickedness of each murder ... you are not only a murderer but a terrorist," he said.
Justice Mander said a finite term would not be sufficient given the gravity of the crimes.
"Your crimes, however, are so wicked that even if you are detained until you die it will not exhaust the requirements of punishment and denunciation," he said.
"As far as I can discern, you are empty of any empathy for your victims."
The gunman initially pleaded not guilty to all charges against him but later admitted to 51 charges of murder, 40 counts of attempted murder and one charge of committing a terrorist act during the 2019 shooting rampage at two Christchurch mosques, which he livestreamed on Facebook.
Gamal Fouda, the imam at the Al Noor mosque, told reporters outside the court that no punishment would bring people’s loved ones back, but he was proud of New Zealand's response against extremism.
“All extremists, they represent hate, but we are here today,” he said.
“We represent love, compassion, Muslim and non-Muslim people of faith and of no faith. That is us, New Zealanders, and we are very proud that we are Muslims in New Zealand.”
Victims have said they have found power and strength in giving their impact statements, but equally, some are tired after an emotionally exhausting week.
"He doesn't have the guts (to speak) after being told over and over again what kind of man he is," one told AAP.
"He is defeated. He doesn't want to see eye-to-eye his victims any more. Hate has been silenced."
Christchurch victim's families give heartbreaking testimonies on day two of hearing
New Zealand Prime Minister Jacinda Ardern says the terrorist deserves a "lifetime of complete and utter silence".
Ms Ardern, who was widely praised for the way she handled the aftermath of the attack, said on Thursday that people should forget the gunman's name.
"The trauma of March 15 is not easily healed. But today I hope is the last where we have any cause to hear or utter the name of the terrorist behind it," she said.
"His deserves to be a lifetime of complete and utter silence."
Prime Minister Scott Morrison has welcomed the life sentence given to the gunman, but downplayed the prospect of him serving his prison sentence in Australia.
“This is not a matter which Prime Minister Ardern has raised with me,” he told reporters in Canberra on Thursday.